code: @GwtIncompatible("incompatible method")
    public static void isAssignable(final Class<?> superType, final Class<?> subType) {
      Assert.isAssignable(superType, subType, "");
    }
docs: Assert that {@code superType.isAssignableFrom(subType)} is {@code true}.
  
  <pre class="code">
  Assert.isAssignable(Number.class, myClass);
  </pre>
  
  @param superType the super type to check
  @param subType the sub type to check
  @throws IllegalArgumentException if the classes are not assignable