@java.lang.Override
    public boolean hasFileName() {
      return ((bitField0_ & 0x00000004) != 0);
    }
<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>

@return Whether the fileName field is set.
java-trace/proto-google-cloud-trace-v2/src/main/java/com/google/devtools/cloudtrace/v2/StackTrace.java