code: public static Principal getAuthenticatedPrincipalFrom(Assertion assertion) {
  		final List<Authentication> chain = assertion.getChainedAuthentications();
  		final Principal principal = chain.get(chain.size() - 1).getPrincipal();
  		return principal;
  	}
docs: Extracts an authenticated ${@link Principal} from a provided ${@link Assertion} instance.
  <p/>
  It is a caller's of this method responsibility to ensure that provided ${@link Assertion} instance is not null
  to avoid NPE at runtime.
  
  @param assertion instance to retrieve ${@link Principal} from
  @return Authenticated Principal
  @throws NullPointerException if provided Assertion is <i>null</i>