JDK 10 RFR JDK-8171194: Exception "Duplicate field name&signature in class file" should report the name and signature of the field

[Shafi Ahmad]

Summary: java.lang.ClassFormatError: Exception "Duplicate field name&signature in class file" should report the name and signature of the field.

It's a very small change to single file. 
In the current implementation name and signature of duplicate field is missing in java.lang.ClassFormatError exception message. 
Without a field name + signature it is hard to triggering the problem.

Webrev link: http://cr.openjdk.java.net/~shshahma/8171194/webrev.00/
bug link: https://bugs.openjdk.java.net/browse/JDK-8171194

Testing: jprt and jtreg test.

I have verified my changes with the reproduces of https://bugs.openjdk.java.net/browse/JDK-8080842 on jdk8u60-b01 code base as I was not able to write reproducer of current issue.
With the fix I am getting below exception message.

$ java CreateBadClassFile
.foreach() call: Exception in thread "main" java.lang.ClassFormatError: Duplicate field name "hasNext" with signature "Ljava.lang.Object;" in class file WidgetCollection$1
	at java.lang.ClassLoader.defineClass1(Native Method)
	at java.lang.ClassLoader.defineClass(ClassLoader.java:760)
	at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
               . . . 

Thanks,
Coleen