code: public static boolean isAssignableOrConvertibleFrom(Class<?> clazz, Class<?> type) {
          if (type == null || clazz == null) {
              return false;
          }
          if (type.isPrimitive()) {
              // convert primitive type to compatible class
              Class<?> primitiveClass = GrailsClassUtils.PRIMITIVE_TYPE_COMPATIBLE_CLASSES.get(type);
              if (primitiveClass == null) {
                  // no compatible class found for primitive type
                  return false;
              }
              return clazz.isAssignableFrom(primitiveClass);
          }
          return clazz.isAssignableFrom(type);
      }
docs: Returns true if the specified clazz parameter is either the same as, or is a superclass or superinterface
  of, the specified type parameter. Converts primitive types to compatible class automatically.
  
  @param clazz
  @param type
  @return true if the class is a taglib
  @see java.lang.Class#isAssignableFrom(Class)