public Builder clearId() {
          bitField0_ = (bitField0_ & ~0x00000002);
          id_ = 0L;
          onChanged();
          return this;
        }
<pre>
An identifier for the MessageEvent's message that can be used to match
`SENT` and `RECEIVED` MessageEvents.
</pre>

<code>int64 id = 2;</code>

@return This builder for chaining.
java-trace/proto-google-cloud-trace-v2/src/main/java/com/google/devtools/cloudtrace/v2/Span.java