They are handled automatically by **FastAPI** and converted to JSON.

///

## Add custom headers

There are some situations in where it's useful to be able to add custom headers to the HTTP error. For example, for some types of security.

You probably won't need to use it directly in your code.

But in case you needed it for an advanced scenario, you can add custom headers:

```Python hl_lines="14"

    @Override
    public Builder<E> add(E element) {
      contents.add(checkNotNull(element));
      return this;
    }

    @CanIgnoreReturnValue
    @Override
    public Builder<E> addAll(Iterable<? extends E> elements) {
      super.addAll(elements);
      return this;
    }

    @CanIgnoreReturnValue
    @Override
    public Builder<E> add(E... elements) {

     *
     * @param elements the {@code Iterable} to add to the {@code ImmutableList}
     * @return this {@code Builder} object
     * @throws NullPointerException if {@code elements} is null or contains a null element
     */
    @CanIgnoreReturnValue
    @Override
    public Builder<E> add(E... elements) {
      checkElementsNotNull(elements);
      add(elements, elements.length);
      return this;
    }

        this.notifyInformation.add(i);

        while ( i.getNextEntryOffset() > 0 && bufferIndex < bufferOffset + len ) {
            bufferIndex = elemStart + i.getNextEntryOffset();
            elemStart = bufferIndex;

            i = new FileNotifyInformationImpl();
            bufferIndex += i.decode(buffer, bufferIndex, len);
            this.notifyInformation.add(i);
        }

        if ("g".equals(artifact.getArtifactId())) {
            Artifact a = null;
            try {
                a = factory.createBuildArtifact("org.apache.maven", "h", "1.0", "jar");
                dependencies.add(a);
            } catch (Exception e) {
                throw new ArtifactMetadataRetrievalException("Error retrieving metadata", e, a);
            }
        }

        if ("i".equals(artifact.getArtifactId())) {

            seg.appendChild(document.createTextNode("Each "));
            seg.appendChild(linkRenderer.link(blockDoc.getType(), listener));
            seg.appendChild(document.createTextNode(" in "));
            // TODO - add linkRenderer.link(property)
            Element link = document.createElement("link");
            seg.appendChild(link);
            link.setAttribute("linkend", blockDoc.getBlockProperty().getId());

      commonAddLenient(headers.name(i), headers.value(i))
    }
  }

internal fun Headers.Builder.commonAddLenient(
  name: String,
  value: String,
) = apply {
  namesAndValues.add(name)
  namesAndValues.add(value.trim())
}

internal fun Headers.Builder.commonRemoveAll(name: String) =
  apply {
    var i = 0
    while (i < namesAndValues.size) {

            final String[] oldLabels = DocumentUtil.getValue(dataMap, fessConfig.getIndexFieldLabel(), String[].class);
            StreamUtil.stream(oldLabels).of(stream -> stream.forEach(newLabelSet::add));
            matchedLabelSet.stream().forEach(newLabelSet::add);
            dataMap.put(fessConfig.getIndexFieldLabel(), newLabelSet.toArray(new String[newLabelSet.size()]));
        }

        if (!dataMap.containsKey(fessConfig.getIndexFieldDocId())) {

Now let's jump to the fun stuff. 🎉

## Add `Query` to `Annotated` in the `q` parameter

Now that we have this `Annotated` where we can put more information (in this case some additional validation), add `Query` inside of `Annotated`, and set the parameter `max_length` to `50`:

//// tab | Python 3.10+

```Python hl_lines="9"

    if (count() > 0) {
      return MoreObjects.toStringHelper(this)
          .add("count", count)
          .add("mean", mean)
          .add("populationStandardDeviation", populationStandardDeviation())
          .add("min", min)
          .add("max", max)
          .toString();
    } else {
      return MoreObjects.toStringHelper(this).add("count", count).toString();
    }
  }

  double sumOfSquaresOfDeltas() {