code: @GwtIncompatible("incompatible method")
      public static void isAssignableFrom(final Class<?> superType, final Class<?> type) {
          // TODO when breaking BC, consider returning type
          if (!superType.isAssignableFrom(type)) {
              throw new IllegalArgumentException(StringUtils.simpleFormat(DEFAULT_IS_ASSIGNABLE_EX_MESSAGE, type == null ? "null" : type.getName(),
                      superType.getName()));
          }
      }
docs: Validates that the argument can be converted to the specified class, if not, throws an exception.
  
  <p>This method is useful when validating that there will be no casting errors.</p>
  
  <pre>Validate.isAssignableFrom(SuperClass.class, object.getClass());</pre>
  
  <p>The message format of the exception is &quot;Cannot assign {type} to {superType}&quot;</p>
  
  @param superType  the class the class must be validated against, not null
  @param type  the class to check, not null
  @throws IllegalArgumentException if type argument is not assignable to the specified superType
  @see #isAssignableFrom(Class, Class, String, Object...)
  
  @since 3.0