Reviewed task. Deleting unused method and adjusted some formatting.

Signed-off-by: Juergen Fickel <juergen.fickel@bosch-si.com>

json/src/main/java/org/eclipse/ditto/json/ImmutableJsonObject.java

@@ -315,53 +315,44 @@ public JsonObject get(final JsonFieldSelector fieldSelector) {
 
         if (isEmpty()) {
             return this;
-        } else {
-            final List<JsonPointer> pointersContainedInThis = fieldSelector.getPointers()
-                    .stream()
-                    .filter(this::contains)
-                    .collect(Collectors.toList());
-            if (pointersContainedInThis.isEmpty()) {
-                return JsonFactory.newObject();
-            } else {
-                return filterByTree(this, JsonFieldSelectorTrie.of(pointersContainedInThis));
-            }
         }
-    }
 
-    /*
-     * Build a JsonFieldSelectorTrie ignoring all pointers not contained in this object.
-     */
-    private JsonFieldSelectorTrie trieOfPointersContainedInThis(final Iterable<JsonPointer> jsonPointers) {
-        final JsonFieldSelectorTrie trie = new JsonFieldSelectorTrie();
-        jsonPointers.forEach(jsonPointer -> {
-            if (contains(jsonPointer)) {
-                trie.add(jsonPointer);
-            }
-        });
-        return trie;
+        final List<JsonPointer> pointersContainedInThis = fieldSelector.getPointers()
+                .stream()
+                .filter(this::contains)
+                .collect(Collectors.toList());
+
+        if (pointersContainedInThis.isEmpty()) {
+            return JsonFactory.newObject();
+        } else {
+            return filterByTrie(this, JsonFieldSelectorTrie.of(pointersContainedInThis));
+        }
     }
 
     @SuppressWarnings("unchecked")
-    private static JsonObject filterByTree(final JsonObject me, final JsonFieldSelectorTrie trie) {
+    private static JsonObject filterByTrie(final JsonObject self, final JsonFieldSelectorTrie trie) {
         if (trie.isEmpty()) {
-            return me;
-        } else {
-            final JsonObjectBuilder builder = JsonFactory.newObjectBuilder();
-            trie.getKeys().forEach(key -> {
-                me.getField(key).ifPresent(child -> {
-                    final JsonValue filteredChild = child.getValue().isObject()
-                            ? filterByTree(child.getValue().asObject(), trie.descend(key))
-                            : child.getValue();
-                    final Optional<JsonFieldDefinition> childFieldDefinition = child.getDefinition();
-                    if (childFieldDefinition.isPresent()) {
-                        builder.set(childFieldDefinition.get(), filteredChild);
-                    } else {
-                        builder.set(key, filteredChild);
-                    }
-                });
+            return self;
+        }
+
+        final JsonObjectBuilder builder = JsonFactory.newObjectBuilder();
+
+        for (final JsonKey key : trie.getKeys()) {
+            self.getField(key).ifPresent(child -> {
+                final JsonValue childValue = child.getValue();
+                final JsonValue filteredChildValue = childValue.isObject()
+                        ? filterByTrie(childValue.asObject(), trie.descend(key))
+                        : childValue;
+                final Optional<JsonFieldDefinition> childFieldDefinition = child.getDefinition();
+                if (childFieldDefinition.isPresent()) {
+                    builder.set(childFieldDefinition.get(), filteredChildValue);
+                } else {
+                    builder.set(key, filteredChildValue);
+                }
             });
-            return builder.build();
         }
+
+        return builder.build();
     }
 
     @Override

json/src/main/java/org/eclipse/ditto/json/JsonFieldDefinition.java

@@ -19,8 +19,10 @@
  * A {@code JsonFieldDefinition} is a formal description of a single {@link JsonField}. A JSON field consists of a key
  * (or name) and a value. A JsonFieldDefinition differs in the way that it consists not only of a simple JSON key but
  * its super type {@link JsonPointer}. With the help of this interface one can explicitly define a schema of a JSON
- * document including all sub documents. <p> The following example shows how a JSON document would be described with the
- * help of JsonFieldDefinition.
+ * document including all sub documents.
+ * <p>
+ * The following example shows how a JSON document would be described with the help of JsonFieldDefinition.
+ * </p>
  * <p>
  * <pre>
  *      {
@@ -35,31 +37,35 @@
  * </pre>
  * <p>
  * Within an according class the structure of this JSON document could be described as follows:
+ * </p>
  * <p>
  * <pre>
- *       import static JsonFactory.newFieldDefinition;
- *       ...
+ *    import static JsonFactory.newIntFieldDefinition;
+ *    import static JsonFactory.newStringFieldDefinition;
+ *    ...
  *
- *        public final class Thing {
+ *    public final class Thing {
  *
- *           private static final JsonFieldDefinition THING_ID = newFieldDefinition("thingId", String.class);
- *           private static final JsonFieldDefinition SUBSEL = newFieldDefinition("attributes/someAttr/subsel",
- * int.class);
- *           private static final JsonFieldDefinition ANOTHER_ATTR = newFieldDefinition("attributes/anotherAttr",
- * String.class);
+ *        private static final JsonFieldDefinition THING_ID = newStringFieldDefinition("thingId");
+ *        private static final JsonFieldDefinition SUBSEL = newIntFieldDefinition("attributes/someAttr/subsel");
+ *        private static final JsonFieldDefinition ANOTHER_ATTR = newStringFieldDefinition("attributes/anotherAttr");
  *
- *           ...
+ *       ...
  *
- *        }
+ *    }
  * </pre>
+ * </p>
  * <p>
  * In this case {@code attributes} and {@code someAttr} are implicitly defined with the value type {@link JsonObject}.
+ * </p>
  * <p>
  * Additionally, a JSON field definition can be marked with zero to n {@link JsonFieldMarker}s. The semantics of a
  * marker is defined by you rather than Ditto JSON. One possible usage scenario would be to define the fields which
  * belong to a particular schema version with a maker according to that version.
+ * </p>
  * <p>
  * <em>Implementations of this interface are required to be immutable!</em>
+ * </p>
  */
 public interface JsonFieldDefinition<T> {
 
@@ -134,9 +140,7 @@ static JsonFieldDefinition<Double> ofDouble(final CharSequence pointer, final Js
      * @throws IllegalArgumentException if {@code pointer} is empty.
      * @see JsonFactory#newBooleanFieldDefinition(CharSequence, JsonFieldMarker...)
      */
-    static JsonFieldDefinition<Boolean> ofBoolean(final CharSequence pointer,
-            final JsonFieldMarker ... markers) {
-
+    static JsonFieldDefinition<Boolean> ofBoolean(final CharSequence pointer, final JsonFieldMarker ... markers) {
         return JsonFactory.newBooleanFieldDefinition(pointer, markers);
     }
 
@@ -151,9 +155,7 @@ static JsonFieldDefinition<Boolean> ofBoolean(final CharSequence pointer,
      * @throws IllegalArgumentException if {@code pointer} is empty.
      * @see JsonFactory#newJsonObjectFieldDefinition(CharSequence, JsonFieldMarker...)
      */
-    static JsonFieldDefinition<JsonObject> ofJsonObject(final CharSequence pointer,
-            final JsonFieldMarker ... markers) {
-
+    static JsonFieldDefinition<JsonObject> ofJsonObject(final CharSequence pointer, final JsonFieldMarker ... markers) {
         return JsonFactory.newJsonObjectFieldDefinition(pointer, markers);
     }
 
@@ -168,9 +170,7 @@ static JsonFieldDefinition<JsonObject> ofJsonObject(final CharSequence pointer,
      * @throws IllegalArgumentException if {@code pointer} is empty.
      * @see JsonFactory#newJsonArrayFieldDefinition(CharSequence, JsonFieldMarker...)
      */
-    static JsonFieldDefinition<JsonArray> ofJsonArray(final CharSequence pointer,
-            final JsonFieldMarker ... markers) {
-
+    static JsonFieldDefinition<JsonArray> ofJsonArray(final CharSequence pointer, final JsonFieldMarker ... markers) {
         return JsonFactory.newJsonArrayFieldDefinition(pointer, markers);
     }
 
@@ -185,9 +185,7 @@ static JsonFieldDefinition<JsonArray> ofJsonArray(final CharSequence pointer,
      * @throws IllegalArgumentException if {@code pointer} is empty.
      * @see JsonFactory#newJsonValueFieldDefinition(CharSequence, JsonFieldMarker...)
      */
-    static JsonFieldDefinition<JsonValue> ofJsonValue(final CharSequence pointer,
-            final JsonFieldMarker ... markers) {
-
+    static JsonFieldDefinition<JsonValue> ofJsonValue(final CharSequence pointer, final JsonFieldMarker ... markers) {
         return JsonFactory.newJsonValueFieldDefinition(pointer, markers);
     }
 

json/src/main/java/org/eclipse/ditto/json/JsonFieldSelectorTrie.java

@@ -11,6 +11,8 @@
  */
 package org.eclipse.ditto.json;
 
+import static java.util.Objects.requireNonNull;
+
 import java.util.HashMap;
 import java.util.Iterator;
 import java.util.Map;
@@ -23,11 +25,11 @@
  * a {@code JsonObject} by, since it requires no merging of sub-objects.
  * <p>
  * A normal {@code JsonFieldSelector} is a list of {@code JsonPointer}s, for example:
- * <pre>{@code
- * JsonPointer_1: a -> b -> c -> d
- * JsonPoniter_2: a -> b -> e
- * JsonPointer_3: b -> b -> c
- * }</pre>
+ * <pre>
+ * JsonPointer 1: a -> b -> c -> d
+ * JsonPointer 2: a -> b -> e
+ * JsonPointer 3: b -> b -> c
+ * </pre>
  * {@code JsonFieldSelectorTrie} represents the list as trie by collecting lists with the same prefix:
  * <pre>{@code
  *
@@ -53,54 +55,37 @@ final class JsonFieldSelectorTrie {
     /**
      * Children of the trie.
      */
-    private final Map<JsonKey, JsonFieldSelectorTrie> children = new HashMap<>();
+    private final Map<JsonKey, JsonFieldSelectorTrie> children;
 
-    /**
-     * @return whether this trie has any child.
-     */
-    boolean isEmpty() {
-        return children.isEmpty();
+    private JsonFieldSelectorTrie() {
+        children = new HashMap<>();
     }
 
     /**
-     * @return set of labels of children.
-     */
-    Set<JsonKey> getKeys() {
-        return children.keySet();
-    }
-
-    /**
-     * retrieve a child.
+     * Creates a trie from the specified JsonPointers.
      *
-     * @param key label of the child.
-     * @return the child if it exists; an empty trie if it does not.
+     * @param jsonPointers collection of JSON pointers which form the returned trie.
+     * @return trie representation of the collection.
+     * @throws NullPointerException if {@code jsonPointers} is {@code null}.
      */
-    JsonFieldSelectorTrie descend(final JsonKey key) {
-        final JsonFieldSelectorTrie child = children.get(key);
-        return child != null ? child : new JsonFieldSelectorTrie();
+    static JsonFieldSelectorTrie of(final Iterable<JsonPointer> jsonPointers) {
+        requireNonNull(jsonPointers, "The JSON pointers must not be null!");
+
+        final JsonFieldSelectorTrie trie = new JsonFieldSelectorTrie();
+        jsonPointers.forEach(trie::add);
+        return trie;
     }
 
     /**
-     * Mutate the trie minimally so that the path of JsonKeys in the JsonPointer exists in the trie.
+     * Mutates the trie minimally so that the path of JsonKeys in the JsonPointer exists in the trie.
      *
      * @param jsonPointer the path to expand.
-     * @return this trie after adding the path in json pointer.
+     * @return this trie after adding the path in JSON pointer.
+     * @throws NullPointerException if {@code jsonPointer} is {@code null}.
      */
     JsonFieldSelectorTrie add(final JsonPointer jsonPointer) {
-        final Iterator<JsonKey> iterator = jsonPointer.iterator();
-        return addJsonKeyIterator(iterator);
-    }
-
-    /**
-     * Create a trie from a collection of JsonPointers.
-     *
-     * @param jsonPointers collection of json pointers.
-     * @return trie representation of the collection.
-     */
-    static JsonFieldSelectorTrie of(final Iterable<JsonPointer> jsonPointers) {
-        final JsonFieldSelectorTrie trie = new JsonFieldSelectorTrie();
-        jsonPointers.forEach(trie::add);
-        return trie;
+        requireNonNull(jsonPointer, "The JSON pointer to be added must not be null!");
+        return addJsonKeyIterator(jsonPointer.iterator());
     }
 
     /**
@@ -120,4 +105,34 @@ private JsonFieldSelectorTrie addJsonKeyIterator(final Iterator<JsonKey> iterato
         }
         return this;
     }
+
+    /**
+     * Indicates whether this trie has any child.
+     *
+     * @return {@code true} if this trie has a child, {@code false} else.
+     */
+    boolean isEmpty() {
+        return children.isEmpty();
+    }
+
+    /**
+     * Returns the keys of the children.
+     *
+     * @return the keys.
+     */
+    Set<JsonKey> getKeys() {
+        return children.keySet();
+    }
+
+    /**
+     * Retrieves a child.
+     *
+     * @param key label of the child.
+     * @return the child if it exists; an empty trie if it does not.
+     */
+    JsonFieldSelectorTrie descend(final JsonKey key) {
+        final JsonFieldSelectorTrie child = children.get(key);
+        return child != null ? child : new JsonFieldSelectorTrie();
+    }
+
 }

json/src/test/java/org/eclipse/ditto/json/ImmutableJsonObjectTest.java

@@ -114,7 +114,7 @@ public void orderOfFieldsDoesNotAffectEquality() {
 
     @Test(expected = NullPointerException.class)
     public void tryToGetInstanceFromNullJsonObject() {
-        ImmutableJsonObject.of((Map<String, JsonField>) null);
+        ImmutableJsonObject.of(null);
     }
 
     @Test
@@ -193,7 +193,7 @@ public void setWorksAsExpected() {
     @Test(expected = NullPointerException.class)
     public void tryToSetIntValueWithNullKey() {
         final JsonObject underTest = ImmutableJsonObject.empty();
-        underTest.setValue((String) null, KNOWN_INT_23);
+        underTest.setValue(null, KNOWN_INT_23);
     }
 
     @Test
@@ -409,8 +409,10 @@ public void setValueWithJsonPointerToExistingJsonObject() {
         final JsonObject bazJsonObject = ImmutableJsonObject.of(toMap("baz", KNOWN_INT_23));
 
         final int intValue10 = 10;
-        final JsonObject barJsonObject =
-                JsonFactory.newObjectBuilder().set("bar", bazJsonObject).set("yo", intValue10).build();
+        final JsonObject barJsonObject = JsonFactory.newObjectBuilder()
+                .set("bar", bazJsonObject)
+                .set("yo", intValue10)
+                .build();
 
         final JsonObject underTest = ImmutableJsonObject.of(toMap("foo", barJsonObject));
 
@@ -537,7 +539,7 @@ public void getValueWithPointerFromJsonObjectWithJsonArrayAtSomePointerLevel() {
     @Test(expected = NullPointerException.class)
     public void tryToRemoveJsonFieldByNullName() {
         final JsonObject underTest = ImmutableJsonObject.of(KNOWN_FIELDS);
-        underTest.remove((String) null);
+        underTest.remove(null);
     }
 
     @Test
@@ -570,9 +572,9 @@ public void removingExistingJsonFieldByNameReturnsDisjunctJsonObject() {
         underTest.remove(KNOWN_KEY_BAZ);
 
         assertThat(afterRemoval)
-                .contains(KNOWN_KEY_BAZ, KNOWN_VALUE_BAZ)
                 .as("Another removal on original"
-                        + " JSON object has no influence on the JSON object which was created after first removal.");
+                        + " JSON object has no influence on the JSON object which was created after first removal.")
+                .contains(KNOWN_KEY_BAZ, KNOWN_VALUE_BAZ);
     }
 
     @Test
@@ -1272,8 +1274,7 @@ public void shouldHandleOverlappingFieldSelectors() {
         final JsonObject underTest = JsonFactory.newObject(jsonString);
 
         // a field selector is overlapping if one pointer is a prefix of another.
-        final JsonFieldSelector overlappingSelector =
-                JsonFieldSelector.newInstance("x/y", "x/z", "x");
+        final JsonFieldSelector overlappingSelector = JsonFieldSelector.newInstance("x/y", "x/z", "x");
         final JsonObject actual = underTest.get(overlappingSelector);
 
         assertThat(actual).isEqualTo(underTest.remove("w"));

json/src/test/java/org/eclipse/ditto/json/JsonFieldSelectorTrieTest.java

@@ -23,7 +23,7 @@
 /**
  * Unit test for {@link JsonFieldSelectorTrie}.
  */
-public class JsonFieldSelectorTrieTest {
+public final class JsonFieldSelectorTrieTest {
 
     @Test
     public void trieWithEmptyPathIsEmpty() {
@@ -59,4 +59,5 @@ private static Set<JsonKey> getDescendantKeys(final JsonFieldSelectorTrie trie,
             return trie.getKeys();
         }
     }
+
 }