<T> ServerRequestCallerBuilder<T> newServerCaller() {
    return this.connection.callerFactory.<T> serverRequest()
      .rpcTimeout(rpcTimeoutNs, TimeUnit.NANOSECONDS)
      .operationTimeout(operationTimeoutNs, TimeUnit.NANOSECONDS)
      .pause(pauseNs, TimeUnit.NANOSECONDS)
      .pauseForServerOverloaded(pauseNsForServerOverloaded, TimeUnit.NANOSECONDS)
      .maxAttempts(maxAttempts).startLogErrorsCnt(startLogErrorsCnt);
  }
Get the region info for the passed region name. The region name may be a full region name or
encoded region name. If the region does not found, then it'll throw an UnknownRegionException
wrapped by a {@link CompletableFuture}
@return region info, wrapped by a {@link CompletableFuture}
hbase-client/src/main/java/org/apache/hadoop/hbase/client/RawAsyncHBaseAdmin.java