@java.lang.Override
    public com.google.devtools.cloudtrace.v2.TruncatableStringOrBuilder getFileNameOrBuilder() {
      return fileName_ == null
          ? com.google.devtools.cloudtrace.v2.TruncatableString.getDefaultInstance()
          : fileName_;
    }
<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