public Builder setParentSpanId(long value) {

      parentSpanId_ = value;
      bitField0_ |= 0x00000020;
      onChanged();
      return this;
    }
<pre>
Optional. ID of the parent span, if any.
</pre>

<code>fixed64 parent_span_id = 6 [(.google.api.field_behavior) = OPTIONAL];</code>

@param value The parentSpanId to set.
@return This builder for chaining.
java-trace/proto-google-cloud-trace-v1/src/main/java/com/google/devtools/cloudtrace/v1/TraceSpan.java