retrofit-converters/jackson/src/main/java/retrofit2/converter/jackson/JacksonConverterFactory.java
@SuppressWarnings("ConstantConditions") // Guarding public API nullability.
  public static JacksonConverterFactory create(ObjectMapper mapper) {
    if (mapper == null) throw new NullPointerException("mapper == null");
    return new JacksonConverterFactory(mapper);
  }
@SuppressWarnings("ConstantConditions") // Guarding public API nullability.
  public static JacksonConverterFactory create(ObjectMapper mapper) {
    if (mapper == null) throw new NullPointerException("mapper == null");
    return new JacksonConverterFactory(mapper);
  }
@ SuppressWarnings ( "ConstantConditions" ) // Guarding public API nullability. public static JacksonConverterFactory create ( ObjectMapper mapper ) { if ( mapper == null ) throw new NullPointerException ( "mapper == null" ) ; return new JacksonConverterFactory ( mapper ) ; }
Create an instance using {@code mapper} for conversion.
Create an instance using {