code: public NettyServerBuilder maxConnectionAgeGrace(long maxConnectionAgeGrace, TimeUnit timeUnit) {
      checkArgument(maxConnectionAgeGrace >= 0L, "max connection age grace must be non-negative");
      maxConnectionAgeGraceInNanos = timeUnit.toNanos(maxConnectionAgeGrace);
      if (maxConnectionAgeGraceInNanos >= AS_LARGE_AS_INFINITE) {
        maxConnectionAgeGraceInNanos = MAX_CONNECTION_AGE_GRACE_NANOS_INFINITE;
      }
      return this;
    }
docs: Sets a custom grace time for the graceful connection termination. Once the max connection age
  is reached, RPCs have the grace time to complete. RPCs that do not complete in time will be
  cancelled, allowing the connection to terminate. {@code Long.MAX_VALUE} nano seconds or an
  unreasonably large value are considered infinite.
  
  @see #maxConnectionAge(long, TimeUnit)
  @since 1.3.0