SampleElements<E> samples();

  /**
   * Creates a new container containing the given elements. TODO: would be nice to figure out how to
   * use E... or E[] as a parameter type, but this doesn't seem to work because Java creates an
   * array of the erased type.
   */
  T create(Object... elements);

  /**
   * Helper method to create an array of the appropriate type used by this generator. The returned

    }
    return x;
  }

  @CanIgnoreReturnValue
  static double checkNonNegative(String role, double x) {
    if (!(x >= 0)) { // not x < 0, to work with NaN.
      throw new IllegalArgumentException(role + " (" + x + ") must be >= 0");
    }
    return x;
  }

  static void checkRoundingUnnecessary(boolean condition) {
    if (!condition) {

import org.junit.runners.Parameterized.Parameters;

/** Tests for {@link MapIteratorCache} and {@link MapRetrievalCache}. */
@AndroidIncompatible
// TODO(cpovirk): Figure out Android JUnit 4 support. Does it work with Gingerbread? @RunWith?
@RunWith(Parameterized.class)
@NullUnmarked
public final class MapCacheTest {
  private final MapIteratorCache<String, String> mapCache;

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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
 *

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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
 *

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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
 *

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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
 *

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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
 *

With this, we get tooling support, from editors and mypy as this code is correct in terms of types, but we also get the data filtering from FastAPI.

How does this work? Let's check that out. 🤓

### Type Annotations and Tooling { #type-annotations-and-tooling }

First let's see how editors, mypy and other tools would see this.

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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
 *