static boolean isSigner(
      final Address candidate, final ProtocolContext protocolContext, final BlockHeader parent) {
    final Collection<Address> validators =
        protocolContext
            .getConsensusContext(CliqueContext.class)
            .getValidatorProvider()
            .getValidatorsAfterBlock(parent);
    return validators.contains(candidate);
  }
Is signer.

@param candidate the candidate
@param protocolContext the protocol context
@param parent the parent
@return the boolean
consensus/clique/src/main/java/org/hyperledger/besu/consensus/clique/CliqueHelpers.java