<T> MasterRequestCallerBuilder<T> newMasterCaller() {
    return this.connection.callerFactory.<T> masterRequest()
      .rpcTimeout(rpcTimeoutNs, TimeUnit.NANOSECONDS)
      .operationTimeout(operationTimeoutNs, TimeUnit.NANOSECONDS)
      .pause(pauseNs, TimeUnit.NANOSECONDS)
      .pauseForServerOverloaded(pauseNsForServerOverloaded, TimeUnit.NANOSECONDS)
      .maxAttempts(maxAttempts).startLogErrorsCnt(startLogErrorsCnt);
  }
The implementation of AsyncAdmin.
<p>
The word 'Raw' means that this is a low level class. The returned {@link CompletableFuture} will
be finished inside the rpc framework thread, which means that the callbacks registered to the
{@link CompletableFuture} will also be executed inside the rpc framework thread. So users who use
this class should not try to do time consuming tasks in the callbacks.
@since 2.0.0
@see AsyncHBaseAdmin
@see AsyncConnection#getAdmin()
@see AsyncConnection#getAdminBuilder()
hbase-client/src/main/java/org/apache/hadoop/hbase/client/RawAsyncHBaseAdmin.java