/**
 * The MIT License
 * Copyright (c) 2014-2016 Ilkka Seppälä
 * <p>
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 * <p>
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 * <p>
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */
package com.iluwatar.abstractdocument;

import java.util.List;
import java.util.Map;
import java.util.Objects;
import java.util.Optional;
import java.util.function.Function;
import java.util.stream.Stream;

/**
 * Abstract implementation of Document interface
 */
public abstract class AbstractDocument implements Document {

  private final Map<String, Object> properties;

  protected AbstractDocument(Map<String, Object> properties) {
    Objects.requireNonNull(properties, "properties map is required");
    this.properties = properties;
  }

  @Override
  public Void put(String key, Object value) {
    properties.put(key, value);
    return null;
  }

  @Override
  public Object get(String key) {
    return properties.get(key);
  }

  @Override
  public <T> Stream<T> children(String key, Function<Map<String, Object>, T> constructor) {
    Optional<List<Map<String, Object>>> any = Stream.of(get(key)).filter(el -> el != null)
        .map(el -> (List<Map<String, Object>>) el).findAny();
    return any.isPresent() ? any.get().stream().map(constructor) : Stream.empty();
  }

  @Override
  public String toString() {
    StringBuilder builder = new StringBuilder();
    builder.append(getClass().getName()).append("[");
    properties.entrySet()
        .forEach(e -> builder.append("[").append(e.getKey()).append(" : ").append(e.getValue()).append("]"));
    builder.append("]");
    return builder.toString();
  }

}

@@ -2071,21 +2071,21 @@
 ter(
-el -%3E el != n
+Objects::nonN
 ull)
@@ -2166,31 +2166,24 @@
 any.
-isPresent() ? any.get()
+map(maps -%3E maps
 .str
@@ -2208,24 +2208,33 @@
 tor)
- : 
+).orElseGet(
 Stream
-.
+::
 empty
-(
 );%0A 
@@ -2400,37 +2400,28 @@
 ies.
-entrySet()%0A        .forEach(e
+forEach((key, value)
  -%3E 
@@ -2451,18 +2451,11 @@
 end(
-e.getKey()
+key
 ).ap
@@ -2477,20 +2477,13 @@
 end(
-e.getV
+v
 alue
-()
 ).ap

clean code (#910)