@Override
  public IsAliveHandler getIsAliveHandler() {
    return isAliveHandler;
  }
Constructor that takes a BlockchainQueries, ProtocolSchedule, TransactionPool,
MiningCoordinator, Synchronizer, and IsAliveHandler.

@param blockchainQueries the BlockchainQueries
@param protocolSchedule the ProtocolSchedule
@param transactionPool the TransactionPool
@param miningCoordinator the MiningCoordinator
@param synchronizer the Synchronizer
@param isAliveHandler the IsAliveHandler
ethereum/api/src/main/java/org/hyperledger/besu/ethereum/api/graphql/GraphQLDataFetcherContextImpl.java