public Builder clearStartTime() {
      bitField0_ = (bitField0_ & ~0x00000002);
      startTime_ = null;
      if (startTimeBuilder_ != null) {
        startTimeBuilder_.dispose();
        startTimeBuilder_ = null;
      }
      onChanged();
      return this;
    }
<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