While perhaps not the best solution to the problem of enabling debug information in java classes, it is common to use "make JAVAC_FLAGS=-g" for this purpose. This stopped working recently due to using the name JAVAC_FLAGS for a local variable in CompileJavaModules.gmk. Fixing this problem should be as simple as renaming that local variable.

Of course, the use of unofficial variables to control make should not be discouraged, but until a proper solution for adding -g is implemented, this needs to be fixed.