Currently a lot of boilerplate code & configuration needs to written to
add Java api generation for plugin (based on NSH example):

• https://gerrit.fd.io/r/#/c/2713/1/nsh-plugin/java/jvpp/jvpp_nsh.h
• https://gerrit.fd.io/r/#/c/2713/1/nsh-plugin/java/jvpp/jvpp_nsh.c
• https://gerrit.fd.io/r/#/c/2713/1/nsh-plugin/java/Makefile.am

Investigate if H and C files could be generated + move some part of Makefile to scripts that are visible to all plugins.