### Question:
CliqueBlockInterface implements BlockInterface { @Override public Collection<Address> validatorsInBlock(final BlockHeader header) { return CliqueExtraData.decode(header).getValidators(); }  @Override Address getProposerOfBlock(final BlockHeader header); @Override Address getProposerOfBlock(final org.hyperledger.besu.plugin.data.BlockHeader header); @Override Optional<ValidatorVote> extractVoteFromHeader(final BlockHeader header); static BlockHeaderBuilder createHeaderBuilderWithVoteHeaders(
      final BlockHeaderBuilder builder, final Optional<ValidatorVote> vote); @Override Collection<Address> validatorsInBlock(final BlockHeader header); static boolean isValidVoteValue(final long value); static final Address NO_VOTE_SUBJECT; static final long ADD_NONCE; static final long DROP_NONCE; }### Answer:
@Test public void extractsValidatorsFromHeader() { final BlockHeader header = TestHelpers.createCliqueSignedBlockHeader(headerBuilder, proposerKeys, validatorList); final Collection<Address> extractedValidators = blockInterface.validatorsInBlock(header); assertThat(extractedValidators).isEqualTo(validatorList); }