public Builder addAllSpans(
        java.lang.Iterable<? extends com.google.devtools.cloudtrace.v2.Span> values) {
      if (spansBuilder_ == null) {
        ensureSpansIsMutable();
        com.google.protobuf.AbstractMessageLite.Builder.addAll(values, spans_);
        onChanged();
      } else {
        spansBuilder_.addAllMessages(values);
      }
      return this;
    }
<pre>
Required. A list of new spans. The span names must not match existing
spans, otherwise the results are undefined.
</pre>

<code>
repeated .google.devtools.cloudtrace.v2.Span spans = 2 [(.google.api.field_behavior) = REQUIRED];
</code>
java-trace/proto-google-cloud-trace-v2/src/main/java/com/google/devtools/cloudtrace/v2/BatchWriteSpansRequest.java