@java.lang.Override
    public java.lang.String getTraceId() {
      java.lang.Object ref = traceId_;
      if (ref instanceof java.lang.String) {
        return (java.lang.String) ref;
      } else {
        com.google.protobuf.ByteString bs = (com.google.protobuf.ByteString) ref;
        java.lang.String s = bs.toStringUtf8();
        traceId_ = s;
        return s;
      }
    }
<pre>
The `[TRACE_ID]` for a trace within a project.
</pre>

<code>string trace_id = 1;</code>

@return The traceId.
java-trace/proto-google-cloud-trace-v2/src/main/java/com/google/devtools/cloudtrace/v2/Span.java