integration: hundreds of lines of warnings for Java build

[odeke-em]

I just ran make and got hundreds of warnings for the Java builds which can be seen at:
https://gist.github.com/odeke-em/d9bf7d8c377dcec179eb8059bc539fc8

My Java version is

e$ java -version
java version "9.0.4"
Java(TM) SE Runtime Environment (build 9.0.4+11)
Java HotSpot(TM) 64-Bit Server VM (build 9.0.4+11, mixed mode)

[songy23]

The warnings below are due to google/auto#503:

warning: An exception occurred while looking for AutoValue extensions. No extensions will function. This may be due to a corrupt jar file in the compiler's classpath. Exception: java.util.ServiceConfigurationError: com.google.auto.value.extension.AutoValueExtension: Provider com.google.auto.value.extension.memoized.MemoizeExtension could not be instantiated

Note that we're still using v1.4 AutoValue in OpenCensus. In addition, we don't use the MemoizeExtension in OpenCensus Java.

Other warnings are due to missing param or return for Javadocs. I think you can safely ignore all these warnings, since them won't affect the build.

[odeke-em]

Thanks @songy23! However, won't those warnings affect the output of demos? It would be perhaps nice to get them fixed but they aren't a build blocker as you noted.

[songy23]

I tried to add the --quiet option to ./gradlew install, but it didn't help - the Javadoc warning logs still got logged to the console. Though from Gradle documentation, --quiet should have suppressed the warning logs.

@bogdandrutu @sebright do you know a way to work around this? e.g skip checking Javadoc or do not output the Javadoc warning logs?

[sebright]

I tried --quiet, and it seemed to only suppress the messages logged directly from Gradle, such as ":opencensus-api:compileJava" or "Deprecated Gradle features were used in this build, making it incompatible with Gradle 5.0.", not its plugins. I'm having trouble finding a way to suppress the Javadoc warnings from the command line.

EDIT: We should also fix and/or suppress the warnings in opencensus-java.

[songy23]

A temporary fix is to use the released opencensus version on maven and skip code generation. I think this should work for the demo but we still need to figure out how to reduce the (unnecessary) warnings when building opencensus java.