public Builder setStartTime(com.google.type.TimeOfDay value) {
        if (startTimeBuilder_ == null) {
          if (value == null) {
            throw new NullPointerException();
          }
          startTime_ = value;
        } else {
          startTimeBuilder_.setMessage(value);
        }
        bitField0_ |= 0x00000001;
        onChanged();
        return this;
      }
<pre>
Required. The start time of every automated backup in UTC. It must be set
to the start of an hour. This field is required.
</pre>

<code>.google.type.TimeOfDay start_time = 2 [(.google.api.field_behavior) = REQUIRED];
</code>
java-valkey/proto-google-cloud-valkey-v1/src/main/java/com/google/cloud/memorystore/v1/AutomatedBackupConfig.java