public Builder mergeAttributes(com.google.devtools.cloudtrace.v2.Span.Attributes value) {
      if (attributesBuilder_ == null) {
        if (((bitField0_ & 0x00000040) != 0)
            && attributes_ != null
            && attributes_
                != com.google.devtools.cloudtrace.v2.Span.Attributes.getDefaultInstance()) {
          getAttributesBuilder().mergeFrom(value);
        } else {
          attributes_ = value;
        }
      } else {
        attributesBuilder_.mergeFrom(value);
      }
      if (attributes_ != null) {
        bitField0_ |= 0x00000040;
        onChanged();
      }
      return this;
    }
<pre>
A set of attributes on the span. You can have up to 32 attributes per
span.
</pre>

<code>.google.devtools.cloudtrace.v2.Span.Attributes attributes = 7;</code>
java-trace/proto-google-cloud-trace-v2/src/main/java/com/google/devtools/cloudtrace/v2/Span.java