Got crash when tried to execute these method "lookupNameRefInPool" on the constant pool containing:
   #54 = Utf8 <init>
   #55 = Utf8 ()V
   #68 = NameAndType #54:#55 // "<init>":()V

Used "lookupNameRefInPool(constantPool, 68)" and expect to get String "<init>", but get crash

#
# A fatal error has been detected by the Java Runtime Environment:
#
# SIGSEGV (0xb) at pc=0x00007fbe944a63b4, pid=1415, tid=0x00000000000005a1
#
# JRE version: Java(TM) SE Runtime Environment (9.0) (build 1.9.0-internal-kshefov_2015_09_18_14_21-b00)
# Java VM: Java HotSpot(TM) 64-Bit Server VM (1.9.0-internal-kshefov_2015_09_18_14_21-b00, mixed mode, tiered, jvmci, compressed oops, g1 gc, linux-amd64)
# Problematic frame:
# V [libjvm.so+0x6c63b4] java_lang_String::create_from_symbol(Symbol*, Thread*)+0x14
#
# Core dump will be written. Default location: Core dumps may be processed with "/usr/share/apport/apport %p %s %c %P" (or dumping to /home/kshefov/JTwork/scratch/core.1415)
#
# An error report file with more information is saved as:
# /home/kshefov/JTwork/scratch/hs_err_pid1415.log
#
# If you would like to submit a bug report, please visit:
# http://bugreport.java.com/bugreport/crash.jsp
#

The same issue with "lookupSignatureRefInPool" method.