public Builder setIndex(int value) {
            copyOnWrite();
            instance.setIndex(value);
            return this;
        }
<code>int32 index = 1;</code>

@param value The index to set.
@return This builder for chaining.
turms-client-kotlin/src/main/java/im/turms/client/model/proto/model/user/UserRelationshipGroup.java