Updating to xmlsec 2.0.4: setSignatureSpecNSprefix not available.

We are updating from Java 7 to 8 and from Weblogic 10 to 12.
Therefore, we updated from xmlsec 1.2.0 to 2.0.4.

Some of our unit test utilize:

import org.apache.xml.security.utils.Constants;
...
Constants.setSignatureSpecNSprefix("");

However, it seems that setSignatureSpecNSprefix has being removed in the version 2.0.4.

We can't find any documentation that help us to replace it or find a way around it.

If this is not the place for asking this kind of question, please guide us to where we can.
Thank you for you time.