public Builder clearFileName() {
        bitField0_ = (bitField0_ & ~0x00000004);
        fileName_ = null;
        if (fileNameBuilder_ != null) {
          fileNameBuilder_.dispose();
          fileNameBuilder_ = null;
        }
        onChanged();
        return this;
      }
<pre>
The name of the source file where the function call appears (up to 256
bytes).
</pre>

<code>.google.devtools.cloudtrace.v2.TruncatableString file_name = 3;</code>
java-trace/proto-google-cloud-trace-v2/src/main/java/com/google/devtools/cloudtrace/v2/StackTrace.java