* value is undefined.
     *
     * @return the location of the problem, never {@code null}
     */
    @Nonnull
    String getLocation();

    /**
     * Gets the exception that caused this problem (if any).
     *
     * @return the exception that caused this problem or {@code null} if not applicable
     */
    @Nullable

        </field>
      </fields>
      <codeSegments>
        <codeSegment>
          <version>1.2.0+</version>
          <code>
    @Override
    public String toString() {
        return getLocation();
    }
          </code>
        </codeSegment>
      </codeSegments>
    </class>
  </classes>

        </field>
      </fields>
      <codeSegments>
        <codeSegment>
          <version>2.0.0+</version>
          <code>
    @Override
    public String toString() {
        return getLocation();
    }
          </code>
        </codeSegment>
      </codeSegments>
    </class>
  </classes>

      <codeSegments>
        <codeSegment>
          <version>4.0.0+</version>
          <code>
            <![CDATA[
    @Override
    public String toString() {
        return getModelId() + " " + getLocation();
    }
            ]]>
          </code>
        </codeSegment>
      </codeSegments>
    </class>
  </classes>