public Set<Feature<? super Collection>> getImpliedFeatures() {
    return implied;
  }

  public int getNumElements() {
    if (numElements == null) {
      throw new IllegalStateException(
          "A compound CollectionSize doesn't specify a number of elements.");
    }
    return numElements;
  }

  @Retention(RetentionPolicy.RUNTIME)
  @Inherited
  @TesterAnnotation
  public @interface Require {

    }
    return false;
  }

  @Override
  public int hashCode() {
    return Arrays.hashCode(comparators);
  }

  @Override
  public String toString() {
    return "Ordering.compound(" + Arrays.toString(comparators) + ")";
  }

  private static final long serialVersionUID = 0;

    }
    return false;
  }

  @Override
  public int hashCode() {
    return Arrays.hashCode(comparators);
  }

  @Override
  public String toString() {
    return "Ordering.compound(" + Arrays.toString(comparators) + ")";
  }

  private static final long serialVersionUID = 0;

  public Set<Feature<? super Collection>> getImpliedFeatures() {
    return implied;
  }

  public int getNumElements() {
    if (numElements == null) {
      throw new IllegalStateException(
          "A compound CollectionSize doesn't specify a number of elements.");
    }
    return numElements;
  }

  @Retention(RetentionPolicy.RUNTIME)
  @Inherited
  @TesterAnnotation
  public @interface Require {

#       requires all of these POSIX shell features:
#         * functions;
#         * expansions «$var», «${var}», «${var:-default}», «${var+SET}»,
#           «${var#prefix}», «${var%suffix}», and «$( cmd )»;
#         * compound commands having a testable exit status, especially «case»;
#         * various built-in commands including «command», «set», and «ulimit».
#
#   Important for patching:
#

    assertThat("hello".map()).isEqualTo("hello")
    assertThat("hello-world".map()).isEqualTo("hello-world")
    assertThat("HELLO".map()).isEqualTo("hello")
    assertThat("Hello".map()).isEqualTo("hello")

    // These compound characters map their its components.
    assertThat("¼".map()).isEqualTo("1⁄4")
    assertThat("™".map()).isEqualTo("tm")
  }

  /** Confirm the compact table satisfies is documented invariants. */

**FastAPI** will do the automatic conversion from the request, so that the parameter `item` receives it's specific content and the same for `user`.

It will perform the validation of the compound data, and will document it like that for the OpenAPI schema and automatic docs.

## Singular values in body