public Builder clearFunctionName() {
        bitField0_ = (bitField0_ & ~0x00000001);
        functionName_ = null;
        if (functionNameBuilder_ != null) {
          functionNameBuilder_.dispose();
          functionNameBuilder_ = null;
        }
        onChanged();
        return this;
      }
<pre>
The fully-qualified name that uniquely identifies the function or
method that is active in this frame (up to 1024 bytes).
</pre>

<code>.google.devtools.cloudtrace.v2.TruncatableString function_name = 1;</code>
java-trace/proto-google-cloud-trace-v2/src/main/java/com/google/devtools/cloudtrace/v2/StackTrace.java