Generates an SHA-512 Hash from a given input <tt>source</tt> with an optional <tt>salt</tt> and hash iterations. <p/> See the {@link SimpleHash SimpleHash} parent class JavaDoc for a detailed explanation of Hashing techniques and how the overloaded constructors function. <p/> <b>JDK Version Note</b> - Attempting to instantiate this class on JREs prior to version 1.4.0 will throw an {@link IllegalStateException IllegalStateException}