private boolean updateQualifierOnEquality(DfaVariableValue target, DfaValue value) {
    DfType constraint = target.getDescriptor().getQualifierConstraintFromValue(this, value);
    DfaVariableValue qualifier = target.getQualifier();
    return qualifier == null || meetDfType(qualifier, constraint);
  }
private boolean updateQualifierOnEquality(DfaVariableValue target, DfaValue value)