private ArrayWithDuplicate(E[] elements, E duplicate) {
      this.elements = elements;
      this.duplicate = duplicate;
    }
  }

  /**
   * @return an array of the proper size with a duplicate element. The size must be at least three.
   */
  protected ArrayWithDuplicate<E> createArrayWithDuplicateElement() {
    E[] elements = createSamplesArray();
    E duplicate = elements[(elements.length / 2) - 1];

         *
         * Ideally we'd have a real eviction policy, but until we see a problem in practice, I hope
         * that this will suffice. I have not even benchmarked with different size limits.
         */
        if (validClasses.size() > 1000) {
          validClasses.clear();
        }

        validClasses.add(new WeakReference<Class<? extends Exception>>(exceptionClass));
      }
    }

    /**

        }

        if (_specification != null) {
            builder.setFetchSource(_specification.columnList.toArray(new String[_specification.columnList.size()]), null);
        }

        return builder;
    }

    // ===================================================================================

        }

        if (_specification != null) {
            builder.setFetchSource(_specification.columnList.toArray(new String[_specification.columnList.size()]), null);
        }

        return builder;
    }

    // ===================================================================================

            public Class<? extends Annotation> annotationType() {
                return CustomSize.class;
            }

            @Override
            public String message() {
                return "Size validation failed";
            }

            @Override
            public Class<?>[] groups() {
                return new Class<?>[0];
            }

            @Override

    interfaceClasses.add(Serializable.class);
    Object dummy =
        Proxy.newProxyInstance(
            interfaceClasses.iterator().next().getClassLoader(),
            interfaceClasses.toArray(new Class<?>[interfaceClasses.size()]),
            new DummyHandler(interfaceType));
    @SuppressWarnings("unchecked") // interfaceType is T
    T result = (T) dummy;
    return result;
  }

        transfers.put(
                new TransferResourceIdentifier(resource),
                new TransferResourceAndSize(resource, event.getTransferredBytes()));

        buffer.append("Progress (").append(transfers.size()).append("): ");

        Iterator<TransferResourceAndSize> entries = transfers.values().iterator();
        while (entries.hasNext()) {
            TransferResourceAndSize entry = entries.next();

                // we are already visiting this vertex, this mean we have a cycle
                int pos = cycle.lastIndexOf(v.label);
                List<String> ret = cycle.subList(pos, cycle.size());
                ret.add(v.label);
                return ret;
            }
        }
        return null;
    }

    static class Vertex {
        final String label;

Yani yukarıdaki kod Pydantic'i doğrudan kullanmasa bile, FastAPI bu standart dataclass'ları Pydantic'in kendi dataclass biçimine dönüştürmek için Pydantic'i kullanmaktadır.

Ve elbette aynı özellikleri destekler:

* veri doğrulama (data validation)

/// note | Teknik Detaylar

Bir sonraki örneklerde `from starlette.middleware.something import SomethingMiddleware` kullanmanız da mümkündür.

**FastAPI**, size (geliştirici olarak) kolaylık olsun diye `fastapi.middleware` içinde bazı middleware'leri sağlar. Ancak mevcut middleware'lerin çoğu doğrudan Starlette'ten gelir.

///

## `HTTPSRedirectMiddleware` { #httpsredirectmiddleware }