Upgrade doxia to 2.x stack and code cleanups #88

Job	Run time
Verify / ubuntu-latest jdk-17-zulu 3.9.9	47s
Verify / setup-matrix	1s
Verify / ubuntu-latest jdk-17-zulu 3.6.3	18s
Verify / ubuntu-latest jdk-17-zulu 3.9.9	3s
Verify / ubuntu-latest jdk-21-zulu 3.6.3	21s
Verify / ubuntu-latest jdk-21-zulu 3.9.9	26s
Verify / ubuntu-latest jdk-8-zulu 3.6.3	24s
Verify / ubuntu-latest jdk-8-zulu 3.9.9	25s
Verify / windows-latest jdk-17-zulu 3.6.3	1m 1s
Verify / windows-latest jdk-17-zulu 3.9.9	48s
Verify / windows-latest jdk-21-zulu 3.6.3	1m 5s
Verify / windows-latest jdk-21-zulu 3.9.9	1m 40s
Verify / windows-latest jdk-8-zulu 3.6.3	53s
Verify / windows-latest jdk-8-zulu 3.9.9	58s
Verify / macos-latest jdk-17-zulu 3.6.3	34s
Verify / macos-latest jdk-17-zulu 3.9.9	31s
Verify / macos-latest jdk-21-zulu 3.6.3	34s
Verify / macos-latest jdk-21-zulu 3.9.9	40s
Verify / macos-latest jdk-8-zulu 3.6.3	33s
Verify / macos-latest jdk-8-zulu 3.9.9	25s
	12m 27s

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