content: package com.alibaba.fastjson2.reader;
  
  import com.alibaba.fastjson2.JSONException;
  import com.alibaba.fastjson2.JSONReader;
  import com.alibaba.fastjson2.schema.JSONSchema;
  
  import java.lang.reflect.Field;
  import java.lang.reflect.Type;
  import java.util.Collection;
  import java.util.Collections;
  
  final class FieldReaderCollectionFieldReadOnly<T>
          extends FieldReaderObjectField<T> {
      FieldReaderCollectionFieldReadOnly(
              String fieldName,
              Type fieldType,
              Class fieldClass,
              int ordinal,
              long features,
              String format,
              JSONSchema schema,
              Field field
      ) {
          super(fieldName, fieldType, fieldClass, ordinal, features, format, null, null, schema, field);
      }
  
      @Override
      public void accept(T object, Object value) {
          if (value == null) {
              return;
          }
  
          Collection collection;
          try {
              collection = (Collection) field.get(object);
          } catch (Exception e) {
              throw new JSONException("set " + fieldName + " error", e);
          }
  
          if (collection == Collections.EMPTY_LIST
                  || collection == Collections.EMPTY_SET
                  || collection == null
                  || collection.equals(value)) {
              return;
          }
  
          String name = collection.getClass().getName();
          if ("java.util.Collections$UnmodifiableRandomAccessList".equals(name)
                  || "java.util.Arrays$ArrayList".equals(name)
                  || "java.util.Collections$SingletonList".equals(name)
                  || name.startsWith("java.util.ImmutableCollections$")) {
              return;
          }
  
          collection.addAll((Collection) value);
      }
  
      @Override
      public boolean isReadOnly() {
          return true;
      }
  
      @Override
      public void readFieldValue(JSONReader jsonReader, T object) {
          if (initReader == null) {
              initReader = jsonReader
                      .getContext()
                      .getObjectReader(fieldType);
          }
          Object value = initReader.readObject(jsonReader, fieldType, fieldName, 0);
          accept(object, value);
      }
  }
  