public Builder mergeTraces(com.google.devtools.cloudtrace.v1.Traces value) {
      if (tracesBuilder_ == null) {
        if (((bitField0_ & 0x00000002) != 0)
            && traces_ != null
            && traces_ != com.google.devtools.cloudtrace.v1.Traces.getDefaultInstance()) {
          getTracesBuilder().mergeFrom(value);
        } else {
          traces_ = value;
        }
      } else {
        tracesBuilder_.mergeFrom(value);
      }
      if (traces_ != null) {
        bitField0_ |= 0x00000002;
        onChanged();
      }
      return this;
    }
<pre>
Required. The body of the message.
</pre>

<code>
.google.devtools.cloudtrace.v1.Traces traces = 2 [(.google.api.field_behavior) = REQUIRED];
</code>
java-trace/proto-google-cloud-trace-v1/src/main/java/com/google/devtools/cloudtrace/v1/PatchTracesRequest.java