MNG-5624: Maven API Plugin descriptor xsd does not exist at advertised location

Build has been fixed, but the separate executions appear required. When one execution is used and the XSD is generated the Java source generation breaks.
removed unused imports
[MNG-5630] improved display of forked executions: added phase or goal
[MNG-5631]
 - Cleared WARNINGs during build.
updated javadoc
removed cobertura configuration: it is not in parent any more