val iterator = cache.snapshots()
    assertThat(iterator.hasNext()).isTrue()
    iterator.next().use {
      assertThat(it.key()).isEqualTo("a")
      it.assertValue(0, "a1")
      it.assertValue(1, "a2")
    }
    assertThat(iterator.hasNext()).isTrue()
    iterator.next().use {
      assertThat(it.key()).isEqualTo("b")
      it.assertValue(0, "b1")
      it.assertValue(1, "b2")
    }

        // First call should read the file
        NbtAddress result1 = lmhosts.getByName("TESTHOST", mockContext);
        assertNotNull(result1);

        // Second call should use cached data (file not modified)
        NbtAddress result2 = lmhosts.getByName("TESTHOST", mockContext);
        assertNotNull(result2);
        assertEquals(result1, result2);
    }

    @Test

    }

    @Override
    public V replace(final K key, final V value) {
        // use original key
        return parent.replace(key, value);
    }

    @Override
    public V computeIfAbsent(final K key, final Function<? super K, ? extends V> mappingFunction) {
        // use original key
        return parent.computeIfAbsent(key, mappingFunction);
    }

    @Override

Damit erhalten wir Tool-Unterstützung, vom Editor und mypy, da dieser Code hinsichtlich der Typen korrekt ist, aber wir erhalten auch die Datenfilterung von FastAPI.

Wie funktioniert das? Schauen wir uns das mal an. 🤓

### Typannotationen und Tooling

Sehen wir uns zunächst an, wie Editor, mypy und andere Tools dies sehen würden.

/*
 * Copyright (C) 2008 The Guava Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,

     *
     * @param tc
     *            context to use
     * @param type2
     *            The Type-2 message which this represents a response to.
     * @param targetName
     *            SPN of the target system, optional
     * @param password
     *            The password to use when constructing the response.
     * @param domain

    client.newCall(request).execute().use {
      assertThat(it.protocol).isEqualTo(Protocol.HTTP_2)
      assertThat(it.handshake!!.tlsVersion).isEqualTo(TlsVersion.TLS_1_3)
    }

    client.connectionPool.evictAll()
    assertEquals(0, client.connectionPool.connectionCount())

    client.newCall(request).execute().use {
      assertThat(it.protocol).isEqualTo(Protocol.HTTP_2)

The `TestClient` is based on <a href="https://www.python-httpx.org" class="external-link" target="_blank">HTTPX</a>, and luckily, we can use it directly to test the API.

## Example { #example }

/*
 * Copyright (C) 2024 Square, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,

  public @Nullable B put(TypeToken<? extends @NonNull B> key, @ParametricNullness B value) {
    throw new UnsupportedOperationException("Please use putInstance() instead.");
  }

  /**
   * Not supported. Use {@link #putInstance} instead.
   *
   * @deprecated unsupported operation
   * @throws UnsupportedOperationException always
   */
  @Deprecated
  @Override