public Builder mergeChildSpanCount(com.google.protobuf.Int32Value value) {
      if (childSpanCountBuilder_ == null) {
        if (((bitField0_ & 0x00001000) != 0)
            && childSpanCount_ != null
            && childSpanCount_ != com.google.protobuf.Int32Value.getDefaultInstance()) {
          getChildSpanCountBuilder().mergeFrom(value);
        } else {
          childSpanCount_ = value;
        }
      } else {
        childSpanCountBuilder_.mergeFrom(value);
      }
      if (childSpanCount_ != null) {
        bitField0_ |= 0x00001000;
        onChanged();
      }
      return this;
    }
<pre>
Optional. The number of child spans that were generated while this span
was active. If set, allows implementation to detect missing child spans.
</pre>

<code>
.google.protobuf.Int32Value child_span_count = 13 [(.google.api.field_behavior) = OPTIONAL];
</code>
java-trace/proto-google-cloud-trace-v2/src/main/java/com/google/devtools/cloudtrace/v2/Span.java