public static <T extends Payload> boolean hasDuplicateAuthors(
      final Collection<SignedData<T>> msgs) {
    final long distinctAuthorCount = msgs.stream().map(Authored::getAuthor).distinct().count();
    return distinctAuthorCount != msgs.size();
  }
Has duplicate authors.

@param <T> the type parameter
@param msgs the msgs
@return the boolean
consensus/common/src/main/java/org/hyperledger/besu/consensus/common/bft/validation/ValidationHelpers.java