maven plugin output directory should default to "generated-sources/jsonschema2pojo"

[sdettmer]

I read that Maven convention for the storing location for generated source code is target/generated-sources/PLUGIN, so we should use

target/generated-sources/jsonschema2pojo

as output directory name.

According to https://stackoverflow.com/a/38394608 and https://stackoverflow.com/q/19325525 this is not in Mavens Standard Directory Layout, but it is a common convention.

One official looking page suggest the same:
https://maven.apache.org/guides/mini/guide-generating-sources.html points to http://www.antlr.org/api/maven-plugin/latest/ which says:

The plugin will then produce .java and .tokens files in the output directory target/generated-sources/antlr4/org/foo/bar

Other projects are using "generated-sources/*" as well, for example:

• Netbeans: https://netbeans.org/bugzilla/show_bug.cgi?id=198650
• Eclipse: Usage question - automatically add target/generated-sources/java folder querydsl/apt-maven-plugin#50
• GWT: Generate the module to generated sources by default instead of target  tbroyer/gwt-maven-plugin#35
• ONAP: https://jira.onap.org/browse/SDNC-127

So users may like adding:
<outputDirectory>${project.build.directory}/generated-sources/jsonschema2pojo/</outputDirectory>
to the configuration section in the POM.xml file.

Unless there is a special reason for the current default output directory (java-gen), I think this should be considered as default instead:

target/generated-sources/jsonschema2pojo

[joelittlejohn]

More discussion on the mailing list, initiated by @sdettmer:

https://groups.google.com/forum/#!topic/jsonschema2pojo-users/gkzpNn09TQ0

@sdettmer If you submit a PR for this, I'll merge.

This is probably a breaking change for some people, however since the jsonschema2pojo-maven-plugin itself automatically adds the output directory as a maven 'compile source root' it should not be a breaking change for most users.