code: public MYSELF defaultValueProperty(String... properties) {
  		for (String prop : properties) {
  			String propertyKey = BuilderUtils.isExpression(prop) ? BuilderUtils.getPropertyKey(prop) : prop;
  			this.defaultValueProperties.add(propertyKey);
  		}
  		return myself;
  	}
docs: Registers a property key. The key may be either of the form
  <code>"${custom.foo.bar}"</code> or <code>"custom.foo.bar"</code>.
  
  @param properties
  the property keys to register
  @return this instance for fluent chaining