private String extractSignatureId(UseKeyType useKey,SecurityHeaderType header){
  assert header != null;
  String signatureId=null;
  if (useKey != null) {
    signatureId=useKey.getSig();
    if (header.getSignature() == null || !signatureId.equalsIgnoreCase(header.getSignature().getId())) {
      throw new InvalidSecurityHeaderException("SignatureId from UseKey doesn't match signature from the SecurityHeader");
    }
  }
  return signatureId;
}

private String extractSignatureId ( UseKeyType useKey , SecurityHeaderType header ) { assert header != null ; String signatureId = null ; if ( useKey != null ) { signatureId = useKey . getSig ( ) ; if ( header . getSignature ( ) == null || ! signatureId . equalsIgnoreCase ( header . getSignature ( ) . getId ( ) ) ) { throw new InvalidSecurityHeaderException ( "SignatureId from UseKey doesn't match signature from the SecurityHeader" ) ; } } return signatureId ; }
extracts the signature id from the usekey element and verify that the signature id is valid
