This is because by default, FastAPI will inspect every item inside and make sure it is serializable as JSON, using the same [JSON Compatible Encoder](../tutorial/encoder.md){.internal-link target=_blank} explained in the tutorial. This is what allows you to return **arbitrary objects**, for example database models.

 * the License.
 */

package com.google.common.collect;

import static com.google.common.base.Preconditions.checkNotNull;

import com.google.common.annotations.GwtCompatible;
import java.io.Serializable;
import java.util.NoSuchElementException;
import javax.annotation.CheckForNull;

/**
 * Implementation detail for the internal structure of {@link Range} instances. Represents a unique

import com.google.common.annotations.GwtCompatible;
import com.google.common.base.Preconditions;
import com.google.errorprone.annotations.CanIgnoreReturnValue;
import com.google.errorprone.annotations.Immutable;
import java.io.Serializable;
import java.util.AbstractList;
import java.util.Arrays;
import java.util.Collection;
import java.util.List;
import java.util.RandomAccess;
import java.util.Spliterator;
import java.util.Spliterators;

import com.google.common.annotations.GwtCompatible;
import com.google.common.base.Preconditions;
import com.google.errorprone.annotations.CanIgnoreReturnValue;
import com.google.errorprone.annotations.Immutable;
import java.io.Serializable;
import java.util.AbstractList;
import java.util.Arrays;
import java.util.Collection;
import java.util.List;
import java.util.RandomAccess;
import java.util.Spliterator;
import java.util.Spliterators;

import com.google.common.annotations.GwtIncompatible;
import com.google.common.annotations.J2ktIncompatible;
import com.google.common.base.MoreObjects;
import com.google.common.base.Objects;
import java.io.Serializable;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import javax.annotation.CheckForNull;

/**
 * An immutable value object capturing some basic statistics about a collection of paired double

import com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.GwtIncompatible;
import com.google.common.base.Converter;
import com.google.errorprone.annotations.InlineMe;
import java.io.Serializable;
import java.util.AbstractList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import java.util.RandomAccess;

 * the License.
 */

package com.google.common.collect;

import static com.google.common.base.Preconditions.checkNotNull;

import com.google.common.annotations.GwtCompatible;
import java.io.Serializable;
import java.util.NoSuchElementException;
import javax.annotation.CheckForNull;

/**
 * Implementation detail for the internal structure of {@link Range} instances. Represents a unique

import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.base.Preconditions.checkPositionIndexes;

import com.google.common.annotations.GwtCompatible;
import java.io.Serializable;
import java.util.AbstractList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.List;
import java.util.RandomAccess;
import javax.annotation.CheckForNull;

                MapFeature.GENERAL_PURPOSE,
                MapFeature.FAILS_FAST_ON_CONCURRENT_MODIFICATION,
                CollectionFeature.SUPPORTS_ITERATOR_REMOVE,
                CollectionFeature.SERIALIZABLE,
                CollectionSize.ANY)
            .createTestSuite());
    suite.addTestSuite(HashMultimapTest.class);
    return suite;
  }

  /*

                MapFeature.GENERAL_PURPOSE,
                MapFeature.FAILS_FAST_ON_CONCURRENT_MODIFICATION,
                CollectionFeature.SUPPORTS_ITERATOR_REMOVE,
                CollectionFeature.SERIALIZABLE,
                CollectionSize.ANY)
            .createTestSuite());
    suite.addTestSuite(HashMultimapTest.class);
    return suite;
  }

  /*