UIBean class. "required" property not found when migrating from Struts 2.3.8 to 2.3.24

Hi,
I am migrating from Struts 2.3.8 to 2.3.24.
After changing libraries, i have several compilation errors in my custom tag classes:
My class extend from TextField:

public class CustomTextfield extends TextField{
 .. .
 ... .
  protected void evaluateExtraParams() {
        super.evaluateExtraParams();
        if( required != null){
       . . . . . . . . .

The UIBean class has defined the "required" property in line 458 in 2.3.8, although is missing in 2.3.24

protected String required;

In 2.3.24, this property is missing. It seems that this property has been changed for "requiredLabel".

2.3.8:

        if (required != null) {
            addParameter("required", findValue(required, Boolean.class));
        }

2.3.24:

        if (requiredLabel != null) {
            addParameter("required", findValue(requiredLabel, Boolean.class));
        }

In 2.3.24, the property "required" is in the javadoc ("requiredLabel" no).
I don't know if "required" property has been deprecated, and i have to use "requiredLabel", or if it is a bug.

Please, can you check this issue?

Thanks you and best regards!