@Test
public void failAddingMultipleSignersConcerningTheSameAccount() {

    TransactionBuilder b = new TransactionBuilder(neow);
    exceptionRule.expect(TransactionConfigurationException.class);
    exceptionRule.expectMessage("concerning the same account");
    b.signers(Signer.global(account1.getScriptHash()),
            Signer.calledByEntry(account1.getScriptHash()));
}