public CustomScheduler() {}

    /** A callable class that can reschedule itself using a {@link CustomScheduler}. */
    private final class ReschedulableCallable implements Callable<@Nullable Void> {

      /** The underlying task. */
      private final Runnable wrappedRunnable;

      /** The executor on which this Callable will be scheduled. */
      private final ScheduledExecutorService executor;

# Security Tools

When you need to declare dependencies with OAuth2 scopes you use `Security()`.

But you still need to define what is the dependable, the callable that you pass as a parameter to `Depends()` or `Security()`.

There are multiple tools that you can use to create those dependables, and they get integrated into OpenAPI so they are shown in the automatic docs UI, they can be used by automatically generated clients and SDKs, etc.

  public static class NoOpCallable implements Callable<Object> {
    @Override
    public Object call() {
      return Boolean.TRUE;
    }
  }

  public static final String TEST_STRING = "a test string";

  public static class StringTask implements Callable<String> {
    @Override
    public String call() {
      return TEST_STRING;
    }
  }

from collections.abc import Mapping
from typing import (
    Annotated,
    Any,
    BinaryIO,
    Callable,
    Optional,
    TypeVar,
    cast,
)

from annotated_doc import Doc
from pydantic import GetJsonSchemaHandler
from starlette.datastructures import URL as URL  # noqa: F401
from starlette.datastructures import Address as Address  # noqa: F401
from starlette.datastructures import FormData as FormData  # noqa: F401

# Dependencies - `Depends()` and `Security()`

## `Depends()`

Dependencies are handled mainly with the special function `Depends()` that takes a callable.

Here is the reference for it and its parameters.

You can import it directly from `fastapi`:

```python
from fastapi import Depends
```

::: fastapi.Depends

## `Security()`

import static java.lang.Math.min;
import static java.util.concurrent.Executors.newFixedThreadPool;

import com.google.common.primitives.Ints;
import java.util.List;
import java.util.Random;
import java.util.concurrent.Callable;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.ConcurrentSkipListMap;
import java.util.concurrent.ExecutionException;

    public CustomScheduler() {}

    /** A callable class that can reschedule itself using a {@link CustomScheduler}. */
    private final class ReschedulableCallable implements Callable<@Nullable Void> {

      /** The underlying task. */
      private final Runnable wrappedRunnable;

      /** The executor on which this Callable will be scheduled. */
      private final ScheduledExecutorService executor;

            address.firstCalledName();
            address.nextCalledName(mockContext);
            address.toInetAddress();
            address.unwrap(Address.class);
        }, "All Address interface methods should be callable");
    }

    @Test
    @DisplayName("unwrap method should return correct type when supported")
    void testUnwrapMethodContract() throws Exception {
        // Given

    fakeTicker = new FakeTicker();
  }

  @Test
  public void loader() throws ExecutionException {
    Cache<Integer, Integer> cache = CacheBuilder.newBuilder().build();

    Callable<Integer> loader =
        new Callable<Integer>() {
          private int i = 0;

          @Override
          public Integer call() throws Exception {
            return ++i;
          }
        };

    cache.put(0, 10);

from collections.abc import Iterable, Mapping
from enum import Enum
from typing import Annotated, Any, Callable, Optional, Union

from fastapi._compat import with_info_plain_validator_function
from fastapi.logger import logger
from pydantic import (
    AnyUrl,
    BaseModel,
    Field,
    GetJsonSchemaHandler,
)
from typing_extensions import Literal, TypedDict
from typing_extensions import deprecated as typing_deprecated

try: