constants = populateCache(enumClass);
      }
      return constants;
    }
  }

  /**
   * Returns a serializable converter that converts between strings and {@code enum} values of type
   * {@code enumClass} using {@link Enum#valueOf(Class, String)} and {@link Enum#name()}. The
   * converter will throw an {@code IllegalArgumentException} if the argument is not the name of any
   * enum constant in the specified enum.
   *

 */
package org.codelibs.core.beans.converter;

import static org.codelibs.core.misc.AssertionUtil.assertArgumentNotEmpty;
import static org.codelibs.core.misc.AssertionUtil.assertArgumentNotNull;

import java.text.DecimalFormat;
import java.text.ParseException;

import org.codelibs.core.beans.Converter;
import org.codelibs.core.exception.ParseRuntimeException;

 */
package org.codelibs.core.beans.converter;

import static org.codelibs.core.lang.StringUtil.isEmpty;
import static org.codelibs.core.misc.AssertionUtil.assertArgumentNotEmpty;
import static org.codelibs.core.misc.AssertionUtil.assertArgumentNotNull;

import java.util.Date;

import org.codelibs.core.beans.Converter;
import org.codelibs.core.convert.StringConversionUtil;

 */
package org.codelibs.core.beans.converter;

import static org.codelibs.core.lang.StringUtil.isEmpty;
import static org.codelibs.core.misc.AssertionUtil.assertArgumentNotEmpty;
import static org.codelibs.core.misc.AssertionUtil.assertArgumentNotNull;

import java.util.Date;

import org.codelibs.core.beans.Converter;
import org.codelibs.core.convert.DateConversionUtil;

 */
package org.codelibs.core.beans.converter;

import static org.codelibs.core.lang.StringUtil.isEmpty;
import static org.codelibs.core.misc.AssertionUtil.assertArgumentNotEmpty;
import static org.codelibs.core.misc.AssertionUtil.assertArgumentNotNull;

import java.sql.Time;
import java.util.Date;

import org.codelibs.core.beans.Converter;
import org.codelibs.core.convert.StringConversionUtil;

  public void testConverterToForward() {
    assertEquals("FooBar", UPPER_UNDERSCORE.converterTo(UPPER_CAMEL).convert("FOO_BAR"));
    assertEquals("fooBar", UPPER_UNDERSCORE.converterTo(LOWER_CAMEL).convert("FOO_BAR"));
    assertEquals("FOO_BAR", UPPER_CAMEL.converterTo(UPPER_UNDERSCORE).convert("FooBar"));
    assertEquals("FOO_BAR", LOWER_CAMEL.converterTo(UPPER_UNDERSCORE).convert("fooBar"));
  }

  public void testConverterToBackward() {

Então, mesmo com o código acima que não usa Pydantic explicitamente, o FastAPI está usando Pydantic para converter essas dataclasses padrão para a versão do Pydantic.

E claro, ele suporta o mesmo:

* validação de dados
* serialização de dados
* documentação de dados, etc.

      T defaultType = (T) getFirstTypeParameter(type.getType());
      return defaultType;
    }
    if (type.getRawType() == Converter.class) {
      TypeToken<?> convertFromType = type.resolveType(Converter.class.getTypeParameters()[0]);
      TypeToken<?> convertToType = type.resolveType(Converter.class.getTypeParameters()[1]);
      @SuppressWarnings("unchecked") // returns default for both F and T

  public void testStringConverter_convert() {
    Converter<String, Integer> converter = Ints.stringConverter();
    assertThat(converter.convert("1")).isEqualTo((Integer) 1);
    assertThat(converter.convert("0")).isEqualTo((Integer) 0);
    assertThat(converter.convert("-1")).isEqualTo((Integer) (-1));
    assertThat(converter.convert("0xff")).isEqualTo((Integer) 255);
    assertThat(converter.convert("0xFF")).isEqualTo((Integer) 255);

  public void testStringConverter_convert() {
    Converter<String, Long> converter = Longs.stringConverter();
    assertThat(converter.convert("1")).isEqualTo((Long) 1L);
    assertThat(converter.convert("0")).isEqualTo((Long) 0L);
    assertThat(converter.convert("-1")).isEqualTo((Long) (-1L));
    assertThat(converter.convert("0xff")).isEqualTo((Long) 255L);
    assertThat(converter.convert("0xFF")).isEqualTo((Long) 255L);