code: public Bindable<T> withExistingValue(T existingValue) {
  		Assert.isTrue(
  				existingValue == null || this.type.isArray()
  						|| this.boxedType.resolve().isInstance(existingValue),
  				() -> "ExistingValue must be an instance of " + this.type);
  		Supplier<T> value = (existingValue != null) ? () -> existingValue : null;
  		return new Bindable<>(this.type, this.boxedType, value, NO_ANNOTATIONS);
  	}
docs: Create an updated {@link Bindable} instance with an existing value.
  @param existingValue the existing value
  @return an updated {@link Bindable}