@java.lang.Override
    public Builder clear() {
      super.clear();
      bitField0_ = 0;
      name_ = "";
      spanId_ = "";
      parentSpanId_ = "";
      displayName_ = null;
      if (displayNameBuilder_ != null) {
        displayNameBuilder_.dispose();
        displayNameBuilder_ = null;
      }
      startTime_ = null;
      if (startTimeBuilder_ != null) {
        startTimeBuilder_.dispose();
        startTimeBuilder_ = null;
      }
      endTime_ = null;
      if (endTimeBuilder_ != null) {
        endTimeBuilder_.dispose();
        endTimeBuilder_ = null;
      }
      attributes_ = null;
      if (attributesBuilder_ != null) {
        attributesBuilder_.dispose();
        attributesBuilder_ = null;
      }
      stackTrace_ = null;
      if (stackTraceBuilder_ != null) {
        stackTraceBuilder_.dispose();
        stackTraceBuilder_ = null;
      }
      timeEvents_ = null;
      if (timeEventsBuilder_ != null) {
        timeEventsBuilder_.dispose();
        timeEventsBuilder_ = null;
      }
      links_ = null;
      if (linksBuilder_ != null) {
        linksBuilder_.dispose();
        linksBuilder_ = null;
      }
      status_ = null;
      if (statusBuilder_ != null) {
        statusBuilder_.dispose();
        statusBuilder_ = null;
      }
      sameProcessAsParentSpan_ = null;
      if (sameProcessAsParentSpanBuilder_ != null) {
        sameProcessAsParentSpanBuilder_.dispose();
        sameProcessAsParentSpanBuilder_ = null;
      }
      childSpanCount_ = null;
      if (childSpanCountBuilder_ != null) {
        childSpanCountBuilder_.dispose();
        childSpanCountBuilder_ = null;
      }
      spanKind_ = 0;
      return this;
    }
<pre>
A span represents a single operation within a trace. Spans can be
nested to form a trace tree. Often, a trace contains a root span
that describes the end-to-end latency, and one or more subspans for
its sub-operations.

A trace can also contain multiple root spans, or none at all.
Spans do not need to be contiguous. There might be
gaps or overlaps between spans in a trace.
</pre>

Protobuf type {@code google.devtools.cloudtrace.v2.Span}
java-trace/proto-google-cloud-trace-v2/src/main/java/com/google/devtools/cloudtrace/v2/Span.java