private com.google.protobuf.SingleFieldBuilderV3<
            com.google.type.TimeOfDay,
            com.google.type.TimeOfDay.Builder,
            com.google.type.TimeOfDayOrBuilder>
        getStartTimeFieldBuilder() {
      if (startTimeBuilder_ == null) {
        startTimeBuilder_ =
            new com.google.protobuf.SingleFieldBuilderV3<
                com.google.type.TimeOfDay,
                com.google.type.TimeOfDay.Builder,
                com.google.type.TimeOfDayOrBuilder>(
                getStartTime(), getParentForChildren(), isClean());
        startTime_ = null;
      }
      return startTimeBuilder_;
    }
<pre>
Optional. Start time of the window in UTC.
</pre>

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