You probably remember the work I did on constant pool entries in javac. 
There are two classes called PoolReader/Writer which have been used for 
quite a bit of time in JDK 9. If we think we like the new code (and I 
think it does clean up Pool, ClassWriter, ClassReader quite a bit), I 
think we should forward port this patch to JDK 10

http://hg.openjdk.java.net/valhalla/valhalla9/langtools/rev/009918773810

See also the discussion in javac-dev under subject "constant pool sneak 
peek" and "constant pool sneak peek - part two".