Test implicit additionalItems schema

src/main/lombok/org/leumasjaffe/json/schema/Schema.java

@@ -94,7 +94,7 @@ public class Schema implements Tester {
 			}
 		}
 		ArrayTester items = (ArrayTester) children.get("items");
-		ArrayTester addtlItems = (ArrayTester) children.get("additionalItems");
+		ArrayTester addtlItems = (ArrayTester) children.getOrDefault("additionalItems", ACCEPT);
 		ArrayTester.Status status = items.accepts(JsonHelper.toArray(node));
 		if (status.accepted && !status.unprocessed.isEmpty()) {
 			status = addtlItems.accepts(status.unprocessed);

src/test/java/org/leumasjaffe/json/schema/SchemaTest.java

@@ -150,5 +150,9 @@ public class SchemaTest {
 
 		tests.put("additionalItems", FixedTester.ACCEPT);
 		assertTrue(new Schema(tests).accepts(node));
+
+		tests.remove("additionalItems");
+		assertTrue(new Schema(tests).accepts(node));
 	}
-}
+
+}