Fix Java concurrency issue in feature resolution for old <=3.25.x gen…

[zhangskz]

…code using lazy feature resolution.

This should not impact current gencode from >=4.x.x which resolves features in static init.

Fixes #20599

PiperOrigin-RevId: 738467326

Cherry-pick of fafb0fd

[blakeli0]

Is this UnittestProto generated by protoc 25.x?

[zhangskz]

Yes -- //java/core:v25ConcurrentDescriptorsTest uses UnittestProto from v25 gencode jars.

protobuf/java/core/BUILD.bazel

Lines 667 to 699 in 0e9d0f6

	junit_tests(
	name = "v25_core_tests_jar",
	size = "small",
	srcs = glob(
	["src/test/java/**/*.java"],
	exclude = [
	# Depends on test protos or API changes added in v4.x.x (e.g. editions)
	"src/test/java/com/google/protobuf/TextFormatTest.java",
	"src/test/java/com/google/protobuf/DescriptorsTest.java",
	"src/test/java/com/google/protobuf/DebugFormatTest.java",
	"src/test/java/com/google/protobuf/CodedOutputStreamTest.java",
	"src/test/java/com/google/protobuf/CodedInputStreamTest.java",
	"src/test/java/com/google/protobuf/ProtobufToStringOutputTest.java",
	"src/test/java/com/google/protobuf/FieldPresenceTest.java",
	# Excluded in core_tests
	"src/test/java/com/google/protobuf/DecodeUtf8Test.java",
	"src/test/java/com/google/protobuf/IsValidUtf8Test.java",
	"src/test/java/com/google/protobuf/TestUtil.java",
	"src/test/java/com/google/protobuf/TestUtilLite.java",
	"src/test/java/com/google/protobuf/RuntimeVersionTest.java",
	],
	),
	test_prefix = "v25Jar",
	deps = [
	":core",
	":v25_test_util_jar",
	"//compatibility:v25_test_protos_jar",
	"@protobuf_maven_dev//:com_google_guava_guava",
	"@protobuf_maven_dev//:com_google_truth_truth",
	"@protobuf_maven_dev//:junit_junit",
	"@protobuf_maven_dev//:org_mockito_mockito_core",
	],
	)