public Builder mergeAttributes(com.google.devtools.cloudtrace.v2.Span.Attributes value) {
        if (attributesBuilder_ == null) {
          if (((bitField0_ & 0x00000008) != 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_ |= 0x00000008;
          onChanged();
        }
        return this;
      }
<pre>
A set of attributes on the link. Up to 32 attributes can be
specified per link.
</pre>

<code>.google.devtools.cloudtrace.v2.Span.Attributes attributes = 4;</code>
java-trace/proto-google-cloud-trace-v2/src/main/java/com/google/devtools/cloudtrace/v2/Span.java