Why was the equals() method in java.util.Comparator made abstract?

Why was the equals() method in java.util.Comparator made abstract?

References

Reference NO 1

http://stackoverflow.com/questions/15202292/why-was-the-equals-method-in-java-util-comparator-made-abstract

Reference NO 2

http://download.oracle.com/otn_hosted_doc/coherence/350/com/tangosol/util/extractor/AbstractExtractor.html

Reference NO 3

http://www.techempower.com/blog/2013/03/26/everything-about-java-8/

Reference NO 4

http://developer.android.com/reference/java/util/Comparator.html

Reference NO 5

http://www.stanford.edu/group/networking/netdb/hhg/javadoc/stanford/netdb/NetDB.html

Reference NO 6

http://way2java.com/collections/comparable-vs-comparator/

Reference NO 7

http://www.coderanch.com/t/503229/java/java/override-comparator-equals-method-overrided

Reference NO 8

http://docstore.mik.ua/orelly/java-ent/jnut/ch23_01.htm