The langtools repo provides a launcher script to provide simple direct invocation of the jar files that for the various tools in the repository. (This is a simple script for developers, not the main JDK launcher binary.)

There are two issues that need addressing. 

1. The -ea switch has an incorrect value. It should be -ea:com.sun.tools... and not just -ea:com.sun.tools. (The latter would enable assertions in a class named com.sun.tools.)

2. The scripts currently use "java" to invoke the jar file. With the change to v51 class files, it is less likely that the version of java on the path will be able to run the jar file. The scripts should use a better value than just "java". ${target.java.home}/bin/java seems the obvious choice. [Issue: is ${target.java.home} always an absolute path?]