Contribution guide for java

[pavolloffay]

Contribution guide for java libraries https://github.com/opentracing-contrib/meta/issues/6.

@wu-sheng and @bensigelman could you please review? See also https://github.com/opentracing-contrib/meta/issues/6#issuecomment-273776751.

Think it would be better to move Release Rights to ot-java/RELEASE.md.

[wu-sheng]

@pavolloffay , I will do step by step, by following this guide. And ask you to review the branch.

Let's see whether the guide is enough?

[wu-sheng]

Already send a pull request, https://github.com/opentracing-contrib/java-hprose/pull/3. Can you review it?

[pavolloffay]

@wu-sheng review done. Thanks for step by step replication :+1: .

Couple of things need to me handled here:

1. package name in Bintray should not contain invalid characters. We cold do the convention to match repo name or artifact id. I more like artifact id, repo is linked in bintray package description.
2. release profile to attach javadocs and sources.

[pavolloffay]

@sjoerdtalsma could you please review too?

[pavolloffay]

PR updated:

• note about jar files ignored by .gitignore.
• link to sonatype pom.xml requirements
• reformatted README.md and add link to guide_java

[bhs]

@pavolloffay anything blocking merge on this? Seems like several JVM folks have taken a look at this point.

My only possible request would be to try (?) and get as much of the boilerplate as is possible submitted in its own PR. Sometimes the reviews can be annoying when there's a giant mvnw blob in the middle, etc.

[pavolloffay]

@sjoerdtalsma did you have to create maven packages in bintray before release? Yesterday I released java-okhttp and it failed on: https://travis-ci.org/opentracing-contrib/java-okhttp/builds/199774438

Failed to execute goal org.apache.maven.plugins:maven-deploy-plugin:2.7:deploy (default-deploy) on project opentracing-okhttp-parent: Failed to deploy artifacts: Could not find artifact io.opentracing.contrib:opentracing-okhttp-parent:pom:0.0.1 in bintray (https://api.bintray.com/maven/opentracing/maven/opentracing-okhttp/;publish=1) -> [Help 1]

then when I created package in bintray and deployed again it worked fine.

For now I have added a comment that users should create package in bintray before the first release.

[pavolloffay]

@bensigelman I think it is ready to go in.

[bhs]

@pavolloffay awesome, thank you so much!

[sjoerdtalsma]

@pavolloffay

did you have to create maven packages in bintray before release? Yesterday I released java-okhttp and it failed on: https://travis-ci.org/opentracing-contrib/java-okhttp/builds/199774438

I honestly can't tell you because I did create the packages before release 😉. For my personal github project I'm skipping bintray altogether and sync directly to maven-central instead. Not suggesting we do that with OT, but it's one less indirection in the build that caused a lot of initial confusion for me personally.