Upgrade Jackson dependency to version 2.21.1. (#426)

Replacing deprecated iterator with accessor.

Author: blackwinter

build.gradle

@@ -37,7 +37,7 @@ subprojects {
       'equalsverifier':   '3.8.2',
       'everit':           '1.14.6',
       'guava':            '32.0.1-jre',
-      'jackson':          '2.15.1',
+      'jackson':          '2.21.1',
       'jdk':              '11',
       'jdom':             '2.0.6.1',
       'jena':             '4.10.0',

metafix/src/main/java/org/metafacture/metafix/JsonValue.java

@@ -103,7 +103,7 @@ private Value parse(final JsonNode node) {
             final Value value;
 
             if (node.isObject()) {
-                value = Value.newHash(h -> node.fields().forEachRemaining(e -> h.put(e.getKey(), parse(e.getValue()))));
+                value = Value.newHash(h -> node.properties().forEach(e -> h.put(e.getKey(), parse(e.getValue()))));
             }
             else if (node.isArray()) {
                 value = Value.newArray(a -> node.elements().forEachRemaining(v -> a.add(parse(v))));