public Builder clearTraceId() {
      traceId_ = getDefaultInstance().getTraceId();
      bitField0_ = (bitField0_ & ~0x00000002);
      onChanged();
      return this;
    }
<pre>
Globally unique identifier for the trace. This identifier is a 128-bit
numeric value formatted as a 32-byte hex string. For example,
`382d4f4c6b7bb2f4a972559d9085001d`.
</pre>

<code>string trace_id = 2;</code>

@return This builder for chaining.
java-trace/proto-google-cloud-trace-v1/src/main/java/com/google/devtools/cloudtrace/v1/Trace.java