@java.lang.Override
      public /* nullable */ com.google.devtools.cloudtrace.v2.AttributeValue
          getAttributeMapOrDefault(
              java.lang.String key,
              /* nullable */
              com.google.devtools.cloudtrace.v2.AttributeValue defaultValue) {
        if (key == null) {
          throw new NullPointerException("map key");
        }
        java.util.Map<java.lang.String, com.google.devtools.cloudtrace.v2.AttributeValueOrBuilder>
            map = internalGetMutableAttributeMap().ensureBuilderMap();
        return map.containsKey(key) ? attributeMapConverter.build(map.get(key)) : defaultValue;
      }
<pre>
A set of attributes. Each attribute's key can be up to 128 bytes
long. The value can be a string up to 256 bytes, a signed 64-bit integer,
or the boolean values `true` or `false`. For example:

    "/instance_id": { "string_value": { "value": "my-instance" } }
    "/http/request_bytes": { "int_value": 300 }
    "abc.com/myattribute": { "bool_value": false }
</pre>

<code>map&lt;string, .google.devtools.cloudtrace.v2.AttributeValue&gt; attribute_map = 1;
</code>
java-trace/proto-google-cloud-trace-v2/src/main/java/com/google/devtools/cloudtrace/v2/Span.java