public static com.google.devtools.cloudtrace.v2.StackTrace getDefaultInstance() {
    return DEFAULT_INSTANCE;
  }
<pre>
The hash ID is used to conserve network bandwidth for duplicate
stack traces within a single trace.

Often multiple spans will have identical stack traces.
The first occurrence of a stack trace should contain both the
`stackFrame` content and a value in `stackTraceHashId`.

Subsequent spans within the same request can refer
to that stack trace by only setting `stackTraceHashId`.
</pre>

<code>int64 stack_trace_hash_id = 2;</code>

@return This builder for chaining.
java-trace/proto-google-cloud-trace-v2/src/main/java/com/google/devtools/cloudtrace/v2/StackTrace.java