prepare java decoder for transpilation to Kotlin #621

Job	Run time
Build and test cmake:gcc9	24s
Build and test cmake:clang15	36s
Build and test cmake:clang15:asan	41s
Build and test cmake:clang15:tsan	44s
Build and test cmake:clang15:ubsan	48s
Build and test cmake:qemu-arm-neon-gcc	1m 17s
Build and test cmake-osx:clang	43s
Build and test cmake-osx:gcc	39s
Build and test cmake-win64:msvc-rel	1m 28s
Build and test cmake-win64:msvc-dbg	1m 21s
Build and test fuzz:clang15	30s
Build and test python3.10:clang15	1m 53s
Build and test python3.10-win	54s
Build and test maven	23s
Build and test bazel:root	29s
Build and test bazel:go	1m 3s
Build and test bazel:java	1m 59s
Build and test bazel:research	30s
Build and test bazel-osx:root	1m 49s
Build and test bazel-osx:go	2m 52s
Build and test bazel-osx:java	4m 32s
Build and test bazel-osx:research	1m 11s
Build and test bazel-win:root	1m 53s
Build and test bazel-win:java	6m 4s
Build and test bazel-win:research	1m 45s
	36m 28s

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