code: protected String classnameReplacement(String classname) {
          if (classname.startsWith(COPPER_2X_PACKAGE_PREFIX)) {
              String className3x = classname.replace(COPPER_2X_PACKAGE_PREFIX, COPPER_3_PACKAGE_PREFIX);
              if ((COPPER_3_PACKAGE_PREFIX + COPPER_2X_INTERRUPT_NAME).equals(className3x)) {
                  return COPPER_3_PACKAGE_PREFIX + COPPER_3_INTERRUPT_NAME;
              }
              return className3x;
          }
          return classname;
      }
docs: For downward compatibility, there is a package name replacement during
  deserialization of workflow instances and responses.
  The default implementation ensures downward compatibility to copper &lt;= 2.x.
  @param classname the workflow class name
  @return the adjusted workflow class name