code: private void createDefaultMappers() {
      BooleanMapper booleanMapper = new BooleanMapper();
      CharMapper charMapper = new CharMapper();
      ShortMapper shortMapper = new ShortMapper();
      IntegerMapper integerMapper = new IntegerMapper();
      LongMapper longMapper = new LongMapper();
      FloatMapper floatMapper = new FloatMapper();
      DoubleMapper doubleMapper = new DoubleMapper();
  
      cache.put(boolean.class, booleanMapper);
      cache.put(Boolean.class, booleanMapper);
      cache.put(char.class, charMapper);
      cache.put(Character.class, charMapper);
      cache.put(short.class, shortMapper);
      cache.put(Short.class, shortMapper);
      cache.put(int.class, integerMapper);
      cache.put(Integer.class, integerMapper);
      cache.put(long.class, longMapper);
      cache.put(Long.class, longMapper);
      cache.put(float.class, floatMapper);
      cache.put(Float.class, floatMapper);
      cache.put(double.class, doubleMapper);
      cache.put(Double.class, doubleMapper);
      cache.put(String.class, new StringMapper());
      cache.put(BigDecimal.class, new BigDecimalMapper());
      cache.put(byte[].class, new ByteArrayMapper());
      cache.put(char[].class, new CharArrayMapper());
      cache.put(Date.class, new DateMapper());
      cache.put(Calendar.class, new CalendarMapper());
      cache.put(GeoLocation.class, new GeoLocationMapper());
      cache.put(DatastoreKey.class, new KeyMapper());
      cache.put(LocalDate.class, new LocalDateMapper());
      cache.put(LocalTime.class, new LocalTimeMapper());
      cache.put(LocalDateTime.class, new LocalDateTimeMapper());
      cache.put(OffsetDateTime.class, new OffsetDateTimeMapper());
      cache.put(ZonedDateTime.class, new ZonedDateTimeMapper());
    }
docs: Creates and assigns default Mappers various common types.