code: public static void checkAssignability(Class<?> c1, Class<?> c2) {
  		COMPARISON_TYPE ct1 = COMPARISON_TYPE.fromClass(c1);
  		COMPARISON_TYPE ct2 = COMPARISON_TYPE.fromClass(c2);
  		try {
  			COMPARISON_TYPE.fromOperands(ct1, ct2);
  		} catch (Exception e) {
  			throw DBLogger.newUser("Cannot assign " + c2 + " to " + c1, e);
  		}
  	}
docs: This assumes that comparability implies assignability or convertability...
  @param c1 type #1
  @param c2 type #2