diff --git a/core/crypto/aes_context.cpp b/core/crypto/aes_context.cpp
index 8f91d6c759..a1fa439771 100644
--- a/core/crypto/aes_context.cpp
+++ b/core/crypto/aes_context.cpp
@@ -28,7 +28,7 @@
 /* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                 */
 /**************************************************************************/
 
-#include "core/crypto/aes_context.h"
+#include "aes_context.h"
 
 #include "core/object/class_db.h"
 
diff --git a/core/crypto/aes_context.h b/core/crypto/aes_context.h
index bc13485eff..60ae26fe5e 100644
--- a/core/crypto/aes_context.h
+++ b/core/crypto/aes_context.h
@@ -32,6 +32,7 @@
 
 #include "core/crypto/crypto_core.h"
 #include "core/object/ref_counted.h"
+#include "core/variant/binder_common.h"
 
 class AESContext : public RefCounted {
 	GDCLASS(AESContext, RefCounted);
diff --git a/core/crypto/hashing_context.h b/core/crypto/hashing_context.h
index c441da5056..b9e600b623 100644
--- a/core/crypto/hashing_context.h
+++ b/core/crypto/hashing_context.h
@@ -31,6 +31,7 @@
 #pragma once
 
 #include "core/object/ref_counted.h"
+#include "core/variant/binder_common.h"
 
 class HashingContext : public RefCounted {
 	GDCLASS(HashingContext, RefCounted);
diff --git a/core/io/file_access.h b/core/io/file_access.h
index 77fbc99925..e3302604cb 100644
--- a/core/io/file_access.h
+++ b/core/io/file_access.h
@@ -36,6 +36,7 @@
 #include "core/os/memory.h"
 #include "core/string/ustring.h"
 #include "core/typedefs.h"
+#include "core/variant/binder_common.h"
 
 /**
  * Multi-Platform abstraction for accessing to files.
diff --git a/core/io/file_access_compressed.cpp b/core/io/file_access_compressed.cpp
index 7b020e142d..1ba926de08 100644
--- a/core/io/file_access_compressed.cpp
+++ b/core/io/file_access_compressed.cpp
@@ -30,6 +30,8 @@
 
 #include "file_access_compressed.h"
 
+#include "core/math/math_funcs_binary.h"
+
 void FileAccessCompressed::configure(const String &p_magic, Compression::Mode p_mode, uint32_t p_block_size) {
 	magic = p_magic.ascii().get_data();
 	magic = (magic + "    ").substr(0, 4);
diff --git a/core/io/ip.h b/core/io/ip.h
index bab9625c7e..46a7244dbc 100644
--- a/core/io/ip.h
+++ b/core/io/ip.h
@@ -31,7 +31,7 @@
 #pragma once
 
 #include "core/io/ip_address.h"
-#include "core/os/os.h"
+#include "core/variant/binder_common.h"
 
 template <typename T>
 class TypedArray;
diff --git a/core/io/remote_filesystem_client.cpp b/core/io/remote_filesystem_client.cpp
index e542111588..f637fb6725 100644
--- a/core/io/remote_filesystem_client.cpp
+++ b/core/io/remote_filesystem_client.cpp
@@ -33,6 +33,7 @@
 #include "core/io/dir_access.h"
 #include "core/io/file_access.h"
 #include "core/io/stream_peer_tcp.h"
+#include "core/os/os.h"
 #include "core/string/string_builder.h"
 
 #define FILESYSTEM_CACHE_VERSION 1
diff --git a/core/io/stream_peer_socket.cpp b/core/io/stream_peer_socket.cpp
index 1439447d06..1fa0b3ecfa 100644
--- a/core/io/stream_peer_socket.cpp
+++ b/core/io/stream_peer_socket.cpp
@@ -32,6 +32,7 @@
 #include "stream_peer_socket.compat.inc"
 
 #include "core/object/class_db.h"
+#include "core/os/os.h"
 
 Error StreamPeerSocket::poll() {
 	if (status == STATUS_CONNECTED) {
diff --git a/core/io/stream_peer_tcp.cpp b/core/io/stream_peer_tcp.cpp
index b4071e04e0..e3b6dfb281 100644
--- a/core/io/stream_peer_tcp.cpp
+++ b/core/io/stream_peer_tcp.cpp
@@ -32,6 +32,7 @@
 
 #include "core/config/project_settings.h"
 #include "core/object/class_db.h"
+#include "core/os/os.h"
 
 void StreamPeerTCP::accept_socket(Ref<NetSocket> p_sock, const NetSocket::Address &p_addr) {
 	_sock = p_sock;
diff --git a/core/io/stream_peer_uds.cpp b/core/io/stream_peer_uds.cpp
index aa56b80575..ec70a78dce 100644
--- a/core/io/stream_peer_uds.cpp
+++ b/core/io/stream_peer_uds.cpp
@@ -32,6 +32,7 @@
 
 #include "core/config/project_settings.h"
 #include "core/object/class_db.h"
+#include "core/os/os.h"
 
 void StreamPeerUDS::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("bind", "path"), &StreamPeerUDS::bind);
diff --git a/core/io/xml_parser.h b/core/io/xml_parser.h
index 911d2b11b2..ce742fa7e7 100644
--- a/core/io/xml_parser.h
+++ b/core/io/xml_parser.h
@@ -33,6 +33,7 @@
 #include "core/object/ref_counted.h"
 #include "core/string/ustring.h"
 #include "core/templates/vector.h"
+#include "core/variant/binder_common.h"
 
 /*
   Based on irrXML (see their zlib license). Added mainly for compatibility with their Collada loader.
diff --git a/core/object/ref_counted.h b/core/object/ref_counted.h
index 69b8b70334..fc12d955b1 100644
--- a/core/object/ref_counted.h
+++ b/core/object/ref_counted.h
@@ -30,7 +30,6 @@
 
 #pragma once
 
-#include "core/object/class_db.h"
 #include "core/object/object.h"
 #include "core/templates/safe_refcount.h"
 
@@ -239,40 +238,6 @@ public:
 	void set_ref(const Ref<RefCounted> &p_ref);
 };
 
-template <typename T>
-struct PtrToArg<Ref<T>> {
-	_FORCE_INLINE_ static Ref<T> convert(const void *p_ptr) {
-		if (p_ptr == nullptr) {
-			return Ref<T>();
-		}
-		// p_ptr points to a RefCounted object
-		return Ref<T>(*reinterpret_cast<T *const *>(p_ptr));
-	}
-
-	typedef Ref<T> EncodeT;
-
-	_FORCE_INLINE_ static void encode(Ref<T> p_val, const void *p_ptr) {
-		// p_ptr points to an EncodeT object which is a Ref<T> object.
-		*(const_cast<Ref<RefCounted> *>(reinterpret_cast<const Ref<RefCounted> *>(p_ptr))) = p_val;
-	}
-};
-
-template <typename T>
-struct GetTypeInfo<Ref<T>> {
-	static const Variant::Type VARIANT_TYPE = Variant::OBJECT;
-	static const GodotTypeInfo::Metadata METADATA = GodotTypeInfo::METADATA_NONE;
-
-	static inline PropertyInfo get_class_info() {
-		return PropertyInfo(Variant::OBJECT, String(), PROPERTY_HINT_RESOURCE_TYPE, T::get_class_static());
-	}
-};
-
-template <typename T>
-struct VariantInternalAccessor<Ref<T>> {
-	static _FORCE_INLINE_ Ref<T> get(const Variant *v) { return Ref<T>(*VariantInternal::get_object(v)); }
-	static _FORCE_INLINE_ void set(Variant *v, const Ref<T> &p_ref) { VariantInternal::object_assign(v, p_ref); }
-};
-
 // Zero-constructing Ref initializes reference to nullptr (and thus empty).
 template <typename T>
 struct is_zero_constructible<Ref<T>> : std::true_type {};
diff --git a/core/string/print_string.cpp b/core/string/print_string.cpp
index 7f2607b0b3..e669cf7c7d 100644
--- a/core/string/print_string.cpp
+++ b/core/string/print_string.cpp
@@ -33,6 +33,8 @@
 #include "core/core_globals.h"
 #include "core/os/os.h"
 
+#include <cstdio>
+
 static PrintHandlerList *print_handler_list = nullptr;
 static thread_local bool is_printing = false;
 
diff --git a/core/variant/method_ptrcall.h b/core/variant/method_ptrcall.h
index ff2ae0cd94..3aa15e30dc 100644
--- a/core/variant/method_ptrcall.h
+++ b/core/variant/method_ptrcall.h
@@ -270,9 +270,32 @@ struct PtrToArg<const T *> {
 	}
 };
 
+// This is for Ref.
+
+template <typename T>
+struct PtrToArg<Ref<T>> {
+	_FORCE_INLINE_ static Ref<T> convert(const void *p_ptr) {
+		if (p_ptr == nullptr) {
+			return Ref<T>();
+		}
+		// p_ptr points to a RefCounted object
+		return Ref<T>(*reinterpret_cast<T *const *>(p_ptr));
+	}
+
+	typedef Ref<T> EncodeT;
+
+	_FORCE_INLINE_ static void encode(Ref<T> p_val, const void *p_ptr) {
+		// p_ptr points to an EncodeT object which is a Ref<T> object.
+		*(const_cast<Ref<T> *>(reinterpret_cast<const Ref<T> *>(p_ptr))) = p_val;
+	}
+};
+
 // This is for RequiredParam.
 
-template <class T>
+template <typename T>
+class RequiredParam;
+
+template <typename T>
 struct PtrToArg<RequiredParam<T>> {
 	typedef typename RequiredParam<T>::persistent_type EncodeT;
 
@@ -290,7 +313,10 @@ struct PtrToArg<RequiredParam<T>> {
 
 // This is for RequiredResult.
 
-template <class T>
+template <typename T>
+class RequiredResult;
+
+template <typename T>
 struct PtrToArg<RequiredResult<T>> {
 	typedef typename RequiredResult<T>::ptr_type EncodeT;
 
diff --git a/core/variant/type_info.h b/core/variant/type_info.h
index b3594d5b27..9035c4e80b 100644
--- a/core/variant/type_info.h
+++ b/core/variant/type_info.h
@@ -183,10 +183,20 @@ struct GetTypeInfo<T *, std::enable_if_t<std::is_base_of_v<Object, T>>> {
 	}
 };
 
-template <class T>
+template <typename T>
+struct GetTypeInfo<Ref<T>> {
+	static const Variant::Type VARIANT_TYPE = Variant::OBJECT;
+	static const GodotTypeInfo::Metadata METADATA = GodotTypeInfo::METADATA_NONE;
+
+	static inline PropertyInfo get_class_info() {
+		return PropertyInfo(Variant::OBJECT, String(), PROPERTY_HINT_RESOURCE_TYPE, T::get_class_static());
+	}
+};
+
+template <typename T>
 class RequiredParam;
 
-template <class T>
+template <typename T>
 class RequiredResult;
 
 template <typename T>
diff --git a/core/variant/variant_internal.h b/core/variant/variant_internal.h
index 27ed7ded60..90ec4b2ffe 100644
--- a/core/variant/variant_internal.h
+++ b/core/variant/variant_internal.h
@@ -637,6 +637,12 @@ struct VariantInternalAccessor<Object *> {
 	static _FORCE_INLINE_ void set(Variant *v, const Object *p_value) { VariantInternal::object_assign(v, p_value); }
 };
 
+template <typename T>
+struct VariantInternalAccessor<Ref<T>> {
+	static _FORCE_INLINE_ Ref<T> get(const Variant *v) { return Ref<T>(const_cast<Object *>(*VariantInternal::get_object(v))); }
+	static _FORCE_INLINE_ void set(Variant *v, const Ref<T> &p_ref) { VariantInternal::object_assign(v, p_ref); }
+};
+
 template <class T>
 struct VariantInternalAccessor<RequiredParam<T>> {
 	static _FORCE_INLINE_ RequiredParam<T> get(const Variant *v) { return RequiredParam<T>(Object::cast_to<T>(const_cast<Object *>(*VariantInternal::get_object(v)))); }
diff --git a/editor/export/editor_export_preset.h b/editor/export/editor_export_preset.h
index be6ec66b40..a1cc24f827 100644
--- a/editor/export/editor_export_preset.h
+++ b/editor/export/editor_export_preset.h
@@ -33,6 +33,7 @@
 class EditorExportPlatform;
 
 #include "core/object/ref_counted.h"
+#include "core/variant/binder_common.h"
 
 class EditorExportPreset : public RefCounted {
 	GDCLASS(EditorExportPreset, RefCounted);
diff --git a/modules/mobile_vr/register_types.cpp b/modules/mobile_vr/register_types.cpp
index 4ae0c65a22..0a55a0098e 100644
--- a/modules/mobile_vr/register_types.cpp
+++ b/modules/mobile_vr/register_types.cpp
@@ -32,6 +32,8 @@
 
 #include "mobile_vr_interface.h"
 
+#include "core/object/class_db.h"
+
 Ref<MobileVRInterface> mobile_vr;
 
 void initialize_mobile_vr_module(ModuleInitializationLevel p_level) {
diff --git a/modules/navigation_2d/2d/nav_map_iteration_2d.h b/modules/navigation_2d/2d/nav_map_iteration_2d.h
index 313374b215..f937c2db58 100644
--- a/modules/navigation_2d/2d/nav_map_iteration_2d.h
+++ b/modules/navigation_2d/2d/nav_map_iteration_2d.h
@@ -35,6 +35,7 @@
 #include "nav_mesh_queries_2d.h"
 
 #include "core/math/math_defs.h"
+#include "core/os/rw_lock.h"
 #include "core/os/semaphore.h"
 
 class NavLinkIteration2D;
diff --git a/modules/navigation_2d/nav_link_2d.h b/modules/navigation_2d/nav_link_2d.h
index 91d0f208e5..46d74f97e8 100644
--- a/modules/navigation_2d/nav_link_2d.h
+++ b/modules/navigation_2d/nav_link_2d.h
@@ -31,6 +31,8 @@
 #pragma once
 
 #include "2d/nav_base_iteration_2d.h"
+#include "core/os/rw_lock.h"
+#include "core/variant/binder_common.h"
 #include "nav_base_2d.h"
 #include "nav_utils_2d.h"
 
diff --git a/modules/navigation_2d/nav_map_2d.h b/modules/navigation_2d/nav_map_2d.h
index d1a5237271..b58be55979 100644
--- a/modules/navigation_2d/nav_map_2d.h
+++ b/modules/navigation_2d/nav_map_2d.h
@@ -37,6 +37,7 @@
 
 #include "core/math/math_defs.h"
 #include "core/object/worker_thread_pool.h"
+#include "core/os/rw_lock.h"
 #include "servers/navigation_2d/navigation_constants_2d.h"
 
 #include <KdTree2d.h>
diff --git a/modules/navigation_3d/3d/nav_map_iteration_3d.h b/modules/navigation_3d/3d/nav_map_iteration_3d.h
index 2efade40c8..f840215330 100644
--- a/modules/navigation_3d/3d/nav_map_iteration_3d.h
+++ b/modules/navigation_3d/3d/nav_map_iteration_3d.h
@@ -35,6 +35,7 @@
 #include "nav_mesh_queries_3d.h"
 
 #include "core/math/math_defs.h"
+#include "core/os/rw_lock.h"
 #include "core/os/semaphore.h"
 
 class NavLinkIteration3D;
diff --git a/modules/navigation_3d/nav_link_3d.h b/modules/navigation_3d/nav_link_3d.h
index e6b54d2fa8..27c654322c 100644
--- a/modules/navigation_3d/nav_link_3d.h
+++ b/modules/navigation_3d/nav_link_3d.h
@@ -31,6 +31,7 @@
 #pragma once
 
 #include "3d/nav_base_iteration_3d.h"
+#include "core/os/rw_lock.h"
 #include "nav_base_3d.h"
 #include "nav_utils_3d.h"
 
diff --git a/modules/navigation_3d/nav_map_3d.h b/modules/navigation_3d/nav_map_3d.h
index 0f18dd3454..34d11ee463 100644
--- a/modules/navigation_3d/nav_map_3d.h
+++ b/modules/navigation_3d/nav_map_3d.h
@@ -37,6 +37,7 @@
 
 #include "core/math/math_defs.h"
 #include "core/object/worker_thread_pool.h"
+#include "core/os/rw_lock.h"
 #include "servers/navigation_3d/navigation_constants_3d.h"
 
 #include <KdTree2d.h>
diff --git a/modules/upnp/register_types.cpp b/modules/upnp/register_types.cpp
index 49fdd331cc..7ddfdecc0f 100644
--- a/modules/upnp/register_types.cpp
+++ b/modules/upnp/register_types.cpp
@@ -38,6 +38,8 @@
 #include "upnp_miniupnp.h"
 #endif
 
+#include "core/object/class_db.h"
+
 void initialize_upnp_module(ModuleInitializationLevel p_level) {
 	if (p_level != MODULE_INITIALIZATION_LEVEL_SCENE) {
 		return;
diff --git a/modules/upnp/upnp.h b/modules/upnp/upnp.h
index 00a0523f73..0b3adb185e 100644
--- a/modules/upnp/upnp.h
+++ b/modules/upnp/upnp.h
@@ -33,6 +33,7 @@
 #include "upnp_device.h"
 
 #include "core/object/ref_counted.h"
+#include "core/variant/binder_common.h"
 
 class UPNP : public RefCounted {
 	GDCLASS(UPNP, RefCounted);
diff --git a/modules/upnp/upnp_device.h b/modules/upnp/upnp_device.h
index 146727d93a..64602ea70b 100644
--- a/modules/upnp/upnp_device.h
+++ b/modules/upnp/upnp_device.h
@@ -31,6 +31,7 @@
 #pragma once
 
 #include "core/object/ref_counted.h"
+#include "core/variant/binder_common.h"
 
 class UPNPDevice : public RefCounted {
 	GDCLASS(UPNPDevice, RefCounted);
diff --git a/modules/upnp/upnp_device_miniupnp.cpp b/modules/upnp/upnp_device_miniupnp.cpp
index a1e61df400..19a0f4bf10 100644
--- a/modules/upnp/upnp_device_miniupnp.cpp
+++ b/modules/upnp/upnp_device_miniupnp.cpp
@@ -34,8 +34,14 @@
 
 #include "upnp_miniupnp.h"
 
+#include "core/object/class_db.h"
+
 #include <miniupnpc/upnpcommands.h>
 
+UPNPDevice *UPNPDeviceMiniUPNP::_create(bool p_notify_postinitialize) {
+	return static_cast<UPNPDevice *>(ClassDB::creator<UPNPDeviceMiniUPNP>(p_notify_postinitialize));
+}
+
 void UPNPDeviceMiniUPNP::make_default() {
 	UPNPDevice::_create = UPNPDeviceMiniUPNP::_create;
 }
diff --git a/modules/upnp/upnp_device_miniupnp.h b/modules/upnp/upnp_device_miniupnp.h
index 616ecaa6c1..e691644706 100644
--- a/modules/upnp/upnp_device_miniupnp.h
+++ b/modules/upnp/upnp_device_miniupnp.h
@@ -38,7 +38,7 @@ class UPNPDeviceMiniUPNP : public UPNPDevice {
 	GDCLASS(UPNPDeviceMiniUPNP, UPNPDevice);
 
 private:
-	static UPNPDevice *_create(bool p_notify_postinitialize) { return static_cast<UPNPDevice *>(ClassDB::creator<UPNPDeviceMiniUPNP>(p_notify_postinitialize)); }
+	static UPNPDevice *_create(bool p_notify_postinitialize);
 
 	String description_url;
 	String service_type;
diff --git a/modules/upnp/upnp_miniupnp.cpp b/modules/upnp/upnp_miniupnp.cpp
index e32c19a3bb..6ef7716467 100644
--- a/modules/upnp/upnp_miniupnp.cpp
+++ b/modules/upnp/upnp_miniupnp.cpp
@@ -34,11 +34,17 @@
 
 #include "upnp_device_miniupnp.h"
 
+#include "core/object/class_db.h"
+
 #include <miniupnpc/miniwget.h>
 #include <miniupnpc/upnpcommands.h>
 
 #include <cstdlib>
 
+UPNP *UPNPMiniUPNP::_create(bool p_notify_postinitialize) {
+	return static_cast<UPNP *>(ClassDB::creator<UPNPMiniUPNP>(p_notify_postinitialize));
+}
+
 void UPNPMiniUPNP::make_default() {
 	UPNP::_create = UPNPMiniUPNP::_create;
 }
diff --git a/modules/upnp/upnp_miniupnp.h b/modules/upnp/upnp_miniupnp.h
index d8a4cfe422..725e538e94 100644
--- a/modules/upnp/upnp_miniupnp.h
+++ b/modules/upnp/upnp_miniupnp.h
@@ -40,7 +40,7 @@ class UPNPMiniUPNP : public UPNP {
 	GDCLASS(UPNPMiniUPNP, UPNP);
 
 private:
-	static UPNP *_create(bool p_notify_postinitialize) { return static_cast<UPNP *>(ClassDB::creator<UPNPMiniUPNP>(p_notify_postinitialize)); }
+	static UPNP *_create(bool p_notify_postinitialize);
 
 	String discover_multicast_if = "";
 	int discover_local_port = 0;
diff --git a/modules/webxr/register_types.cpp b/modules/webxr/register_types.cpp
index 139539c24c..31207da3d3 100644
--- a/modules/webxr/register_types.cpp
+++ b/modules/webxr/register_types.cpp
@@ -33,6 +33,8 @@
 #include "webxr_interface.h"
 #include "webxr_interface_js.h"
 
+#include "core/object/class_db.h"
+
 #ifdef WEB_ENABLED
 Ref<WebXRInterfaceJS> webxr;
 #endif
diff --git a/platform/android/api/api.cpp b/platform/android/api/api.cpp
index aa17f78ca2..a5c7a2d272 100644
--- a/platform/android/api/api.cpp
+++ b/platform/android/api/api.cpp
@@ -35,6 +35,7 @@
 #include "jni_singleton.h"
 
 #include "core/config/engine.h"
+#include "core/object/class_db.h"
 
 #if !defined(ANDROID_ENABLED)
 static JavaClassWrapper *java_class_wrapper = nullptr;
diff --git a/platform/android/api/jni_singleton.cpp b/platform/android/api/jni_singleton.cpp
new file mode 100644
index 0000000000..ef35ea0736
--- /dev/null
+++ b/platform/android/api/jni_singleton.cpp
@@ -0,0 +1,77 @@
+/**************************************************************************/
+/*  jni_singleton.cpp                                                     */
+/**************************************************************************/
+/*                         This file is part of:                          */
+/*                             GODOT ENGINE                               */
+/*                        https://godotengine.org                         */
+/**************************************************************************/
+/* Copyright (c) 2014-present Godot Engine contributors (see AUTHORS.md). */
+/* Copyright (c) 2007-2014 Juan Linietsky, Ariel Manzur.                  */
+/*                                                                        */
+/* Permission is hereby granted, free of charge, to any person obtaining  */
+/* a copy of this software and associated documentation files (the        */
+/* "Software"), to deal in the Software without restriction, including    */
+/* without limitation the rights to use, copy, modify, merge, publish,    */
+/* distribute, sublicense, and/or sell copies of the Software, and to     */
+/* permit persons to whom the Software is furnished to do so, subject to  */
+/* the following conditions:                                              */
+/*                                                                        */
+/* The above copyright notice and this permission notice shall be         */
+/* included in all copies or substantial portions of the Software.        */
+/*                                                                        */
+/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,        */
+/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF     */
+/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. */
+/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY   */
+/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,   */
+/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE      */
+/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                 */
+/**************************************************************************/
+
+#include "jni_singleton.h"
+
+#include "core/object/class_db.h"
+
+void JNISingleton::_bind_methods() {
+	ClassDB::bind_method(D_METHOD("has_java_method", "method"), &JNISingleton::has_java_method);
+}
+
+Variant JNISingleton::callp(const StringName &p_method, const Variant **p_args, int p_argcount, Callable::CallError &r_error) {
+	// Godot methods take precedence.
+	Variant ret = Object::callp(p_method, p_args, p_argcount, r_error);
+	if (r_error.error == Callable::CallError::CALL_OK) {
+		return ret;
+	}
+
+	// Check the method we're looking for is in the JNISingleton map.
+	// This is done because JNISingletons register methods differently than wrapped JavaClass / JavaObject to allow
+	// for access to private methods annotated with the @UsedByGodot annotation.
+	// In the future, we should remove access to private methods and require that JNISingletons' methods exposed to
+	// GDScript be all public, similarly to what we do for wrapped JavaClass / JavaObject methods. Doing so will
+	// also allow dropping and deprecating the @UsedByGodot annotation.
+	RBMap<StringName, MethodData>::Element *E = method_map.find(p_method);
+	if (E) {
+		if (wrapped_object.is_valid()) {
+			return wrapped_object->callp(p_method, p_args, p_argcount, r_error);
+		} else {
+			r_error.error = Callable::CallError::CALL_ERROR_INSTANCE_IS_NULL;
+		}
+	}
+	return Variant();
+}
+
+void JNISingleton::add_method(const StringName &p_name, const Vector<Variant::Type> &p_args, Variant::Type p_ret_type) {
+	MethodData md;
+	md.argtypes = p_args;
+	md.ret_type = p_ret_type;
+	method_map[p_name] = md;
+}
+
+void JNISingleton::add_signal(const StringName &p_name, const Vector<Variant::Type> &p_args) {
+	MethodInfo mi;
+	mi.name = p_name;
+	for (int i = 0; i < p_args.size(); i++) {
+		mi.arguments.push_back(PropertyInfo(p_args[i], "arg" + itos(i + 1)));
+	}
+	ADD_SIGNAL(mi);
+}
diff --git a/platform/android/api/jni_singleton.h b/platform/android/api/jni_singleton.h
index 9f6b1cbc5f..f6bafce6ae 100644
--- a/platform/android/api/jni_singleton.h
+++ b/platform/android/api/jni_singleton.h
@@ -32,7 +32,6 @@
 
 #include "java_class_wrapper.h"
 
-#include "core/config/engine.h"
 #include "core/templates/rb_map.h"
 #include "core/variant/variant.h"
 
@@ -48,34 +47,10 @@ class JNISingleton : public Object {
 	Ref<JavaObject> wrapped_object;
 
 protected:
-	static void _bind_methods() {
-		ClassDB::bind_method(D_METHOD("has_java_method", "method"), &JNISingleton::has_java_method);
-	}
+	static void _bind_methods();
 
 public:
-	virtual Variant callp(const StringName &p_method, const Variant **p_args, int p_argcount, Callable::CallError &r_error) override {
-		// Godot methods take precedence.
-		Variant ret = Object::callp(p_method, p_args, p_argcount, r_error);
-		if (r_error.error == Callable::CallError::CALL_OK) {
-			return ret;
-		}
-
-		// Check the method we're looking for is in the JNISingleton map.
-		// This is done because JNISingletons register methods differently than wrapped JavaClass / JavaObject to allow
-		// for access to private methods annotated with the @UsedByGodot annotation.
-		// In the future, we should remove access to private methods and require that JNISingletons' methods exposed to
-		// GDScript be all public, similarly to what we do for wrapped JavaClass / JavaObject methods. Doing so will
-		// also allow dropping and deprecating the @UsedByGodot annotation.
-		RBMap<StringName, MethodData>::Element *E = method_map.find(p_method);
-		if (E) {
-			if (wrapped_object.is_valid()) {
-				return wrapped_object->callp(p_method, p_args, p_argcount, r_error);
-			} else {
-				r_error.error = Callable::CallError::CALL_ERROR_INSTANCE_IS_NULL;
-			}
-		}
-		return Variant();
-	}
+	virtual Variant callp(const StringName &p_method, const Variant **p_args, int p_argcount, Callable::CallError &r_error) override;
 
 	Ref<JavaObject> get_wrapped_object() const {
 		return wrapped_object;
@@ -85,21 +60,9 @@ public:
 		return method_map.has(p_method);
 	}
 
-	void add_method(const StringName &p_name, const Vector<Variant::Type> &p_args, Variant::Type p_ret_type) {
-		MethodData md;
-		md.argtypes = p_args;
-		md.ret_type = p_ret_type;
-		method_map[p_name] = md;
-	}
+	void add_method(const StringName &p_name, const Vector<Variant::Type> &p_args, Variant::Type p_ret_type);
 
-	void add_signal(const StringName &p_name, const Vector<Variant::Type> &p_args) {
-		MethodInfo mi;
-		mi.name = p_name;
-		for (int i = 0; i < p_args.size(); i++) {
-			mi.arguments.push_back(PropertyInfo(p_args[i], "arg" + itos(i + 1)));
-		}
-		ADD_SIGNAL(mi);
-	}
+	void add_signal(const StringName &p_name, const Vector<Variant::Type> &p_args);
 
 	JNISingleton() {}
 
diff --git a/scene/animation/tween.h b/scene/animation/tween.h
index e84ead8cb5..4c0ba917c7 100644
--- a/scene/animation/tween.h
+++ b/scene/animation/tween.h
@@ -31,6 +31,7 @@
 #pragma once
 
 #include "core/object/ref_counted.h"
+#include "core/variant/binder_common.h"
 
 class Tween;
 class Node;
diff --git a/servers/camera/camera_server.h b/servers/camera/camera_server.h
index d0bfaaf71a..a69371e9bb 100644
--- a/servers/camera/camera_server.h
+++ b/servers/camera/camera_server.h
@@ -34,6 +34,7 @@
 #include "core/object/ref_counted.h"
 #include "core/os/thread_safe.h"
 #include "core/templates/rid.h"
+#include "core/variant/binder_common.h"
 
 /**
 	The camera server is a singleton object that gives access to the various
diff --git a/servers/navigation_2d/navigation_path_query_parameters_2d.h b/servers/navigation_2d/navigation_path_query_parameters_2d.h
index 11fa44abd5..c281631d97 100644
--- a/servers/navigation_2d/navigation_path_query_parameters_2d.h
+++ b/servers/navigation_2d/navigation_path_query_parameters_2d.h
@@ -31,6 +31,7 @@
 #pragma once
 
 #include "core/object/ref_counted.h"
+#include "core/variant/binder_common.h"
 #include "servers/navigation_2d/navigation_constants_2d.h"
 
 class NavigationPathQueryParameters2D : public RefCounted {
diff --git a/servers/navigation_2d/navigation_path_query_result_2d.h b/servers/navigation_2d/navigation_path_query_result_2d.h
index 71118f4733..2529c62894 100644
--- a/servers/navigation_2d/navigation_path_query_result_2d.h
+++ b/servers/navigation_2d/navigation_path_query_result_2d.h
@@ -31,6 +31,7 @@
 #pragma once
 
 #include "core/object/ref_counted.h"
+#include "core/variant/binder_common.h"
 #include "core/variant/typed_array.h"
 #include "servers/navigation_2d/navigation_constants_2d.h"
 
diff --git a/servers/navigation_3d/navigation_path_query_parameters_3d.h b/servers/navigation_3d/navigation_path_query_parameters_3d.h
index 760553b557..99364536ee 100644
--- a/servers/navigation_3d/navigation_path_query_parameters_3d.h
+++ b/servers/navigation_3d/navigation_path_query_parameters_3d.h
@@ -31,6 +31,7 @@
 #pragma once
 
 #include "core/object/ref_counted.h"
+#include "core/variant/binder_common.h"
 #include "servers/navigation_3d/navigation_constants_3d.h"
 
 class NavigationPathQueryParameters3D : public RefCounted {
diff --git a/servers/navigation_3d/navigation_path_query_result_3d.h b/servers/navigation_3d/navigation_path_query_result_3d.h
index b73a16f3e9..70fdbc1868 100644
--- a/servers/navigation_3d/navigation_path_query_result_3d.h
+++ b/servers/navigation_3d/navigation_path_query_result_3d.h
@@ -31,6 +31,7 @@
 #pragma once
 
 #include "core/object/ref_counted.h"
+#include "core/variant/binder_common.h"
 #include "core/variant/typed_array.h"
 #include "servers/navigation_3d/navigation_constants_3d.h"
 
diff --git a/servers/xr/xr_interface.h b/servers/xr/xr_interface.h
index 7e138d6023..d1c118bccc 100644
--- a/servers/xr/xr_interface.h
+++ b/servers/xr/xr_interface.h
@@ -32,6 +32,7 @@
 
 #include "core/object/ref_counted.h"
 #include "core/os/thread_safe.h"
+#include "core/variant/binder_common.h"
 
 /**
 	The XR interface is a template class on top of which we build interface to different AR, VR and tracking SDKs.
diff --git a/servers/xr/xr_pose.h b/servers/xr/xr_pose.h
index 647ad1a022..25ad6f1d3a 100644
--- a/servers/xr/xr_pose.h
+++ b/servers/xr/xr_pose.h
@@ -31,6 +31,7 @@
 #pragma once
 
 #include "core/object/ref_counted.h"
+#include "core/variant/binder_common.h"
 
 class XRPose : public RefCounted {
 	GDCLASS(XRPose, RefCounted);
diff --git a/servers/xr/xr_server.h b/servers/xr/xr_server.h
index a5b50bc107..acd55a199a 100644
--- a/servers/xr/xr_server.h
+++ b/servers/xr/xr_server.h
@@ -32,6 +32,7 @@
 
 #include "core/object/ref_counted.h"
 #include "core/os/thread_safe.h"
+#include "core/variant/binder_common.h"
 #include "core/variant/variant.h"
 
 class XRInterface;
diff --git a/tests/core/io/test_tcp_server.cpp b/tests/core/io/test_tcp_server.cpp
index 0c035fc510..aa530000a4 100644
--- a/tests/core/io/test_tcp_server.cpp
+++ b/tests/core/io/test_tcp_server.cpp
@@ -35,6 +35,7 @@ TEST_FORCE_LINK(test_tcp_server)
 #include "core/config/project_settings.h"
 #include "core/io/stream_peer_tcp.h"
 #include "core/io/tcp_server.h"
+#include "core/os/os.h"
 
 #include <functional>
 
diff --git a/tests/core/io/test_udp_server.cpp b/tests/core/io/test_udp_server.cpp
index fb7f08ea5c..84e8cf8157 100644
--- a/tests/core/io/test_udp_server.cpp
+++ b/tests/core/io/test_udp_server.cpp
@@ -34,6 +34,7 @@ TEST_FORCE_LINK(test_udp_server)
 
 #include "core/io/packet_peer_udp.h"
 #include "core/io/udp_server.h"
+#include "core/os/os.h"
 
 #include <functional>
 
diff --git a/tests/core/io/test_uds_server.cpp b/tests/core/io/test_uds_server.cpp
index 749732b624..b796abda46 100644
--- a/tests/core/io/test_uds_server.cpp
+++ b/tests/core/io/test_uds_server.cpp
@@ -38,6 +38,7 @@ TEST_FORCE_LINK(test_uds_server)
 #include "core/io/file_access.h"
 #include "core/io/stream_peer_uds.h"
 #include "core/io/uds_server.h"
+#include "core/os/os.h"
 
 #include <functional>
 
diff --git a/tests/core/threads/test_worker_thread_pool.cpp b/tests/core/threads/test_worker_thread_pool.cpp
index 7b5b2fae0e..f90e42d475 100644
--- a/tests/core/threads/test_worker_thread_pool.cpp
+++ b/tests/core/threads/test_worker_thread_pool.cpp
@@ -32,6 +32,7 @@
 
 TEST_FORCE_LINK(test_worker_thread_pool)
 
+#include "core/object/callable_method_pointer.h"
 #include "core/object/worker_thread_pool.h"
 
 namespace TestWorkerThreadPool {