From 157f2c490003c7494af8ecb7d57880cda1fde736 Mon Sep 17 00:00:00 2001
From: Tatu Saloranta <tatu.saloranta@iki.fi>
Date: Tue, 11 Dec 2018 22:06:44 -0800
Subject: [PATCH] Fix #502

---
 release-notes/VERSION-2.x                         |  1 +
 .../jackson/core/util/DefaultPrettyPrinter.java   |  6 +++++-
 .../java/com/fasterxml/jackson/core/BaseTest.java |  7 ++++++-
 .../core/util/TestDefaultPrettyPrinter.java       | 15 +++++++++++++++
 4 files changed, 27 insertions(+), 2 deletions(-)

diff --git a/release-notes/VERSION-2.x b/release-notes/VERSION-2.x
index 925d72c5eb..1972f80c0c 100644
--- a/release-notes/VERSION-2.x
+++ b/release-notes/VERSION-2.x
@@ -25,6 +25,7 @@ JSON library.
   `writeRaw(..)`) more efficiently
 #495: Create `StreamReadFeature` to move non-json specific `JsonParser.Feature`s to
 #496: Create `StreamWriteFeature` to take over non-json-specific `JsonGenerator.Feature`s
+#502: Make `DefaultPrettyPrinter.createInstance()` to fail for sub-classes
 
 2.9.8 (not yet released)
 
diff --git a/src/main/java/com/fasterxml/jackson/core/util/DefaultPrettyPrinter.java b/src/main/java/com/fasterxml/jackson/core/util/DefaultPrettyPrinter.java
index d56b16fcf9..7e8250efaf 100644
--- a/src/main/java/com/fasterxml/jackson/core/util/DefaultPrettyPrinter.java
+++ b/src/main/java/com/fasterxml/jackson/core/util/DefaultPrettyPrinter.java
@@ -157,7 +157,7 @@ public DefaultPrettyPrinter withRootSeparator(SerializableString rootSeparator)
     }
 
     /**
-     * @since 2.6.0
+     * @since 2.6
      */
     public DefaultPrettyPrinter withRootSeparator(String rootSeparator) {
         return withRootSeparator((rootSeparator == null) ? null : new SerializedString(rootSeparator));
@@ -252,6 +252,10 @@ public DefaultPrettyPrinter withSeparators(Separators separators) {
 
     @Override
     public DefaultPrettyPrinter createInstance() {
+        if (getClass() != DefaultPrettyPrinter.class) { // since 2.10
+            throw new IllegalStateException("Failed `createInstance()`: "+getClass().getName()
+                    +" does not override method; it has to");
+        }
         return new DefaultPrettyPrinter(this);
     }
 
diff --git a/src/test/java/com/fasterxml/jackson/core/BaseTest.java b/src/test/java/com/fasterxml/jackson/core/BaseTest.java
index 90f75897b6..b3182d6cf2 100644
--- a/src/test/java/com/fasterxml/jackson/core/BaseTest.java
+++ b/src/test/java/com/fasterxml/jackson/core/BaseTest.java
@@ -566,7 +566,12 @@ protected JsonFactory sharedStreamFactory() {
     protected JsonFactory newStreamFactory() {
         return new JsonFactory();
     }
-    
+
+    // @since 2.9.8
+    protected JsonFactoryBuilder streamFactoryBuilder() {
+        return (JsonFactoryBuilder) JsonFactory.builder();
+    }
+
     protected String fieldNameFor(int index)
     {
         StringBuilder sb = new StringBuilder(16);
diff --git a/src/test/java/com/fasterxml/jackson/core/util/TestDefaultPrettyPrinter.java b/src/test/java/com/fasterxml/jackson/core/util/TestDefaultPrettyPrinter.java
index ad1a7e7f08..6a56a049f9 100644
--- a/src/test/java/com/fasterxml/jackson/core/util/TestDefaultPrettyPrinter.java
+++ b/src/test/java/com/fasterxml/jackson/core/util/TestDefaultPrettyPrinter.java
@@ -159,4 +159,19 @@ private String _printTestData(PrettyPrinter pp, boolean useBytes) throws IOExcep
         }
         return sw.toString();
     }
+
+    // [core#502]: Force sub-classes to reimplement `createInstance`
+    public void testInvalidSubClass() throws Exception
+    {
+        DefaultPrettyPrinter pp = new MyPrettyPrinter();
+        try {
+            pp.createInstance();
+            fail("Should not pass");
+        } catch (IllegalStateException e) {
+            verifyException(e, "does not override");
+        }
+    }
+
+    @SuppressWarnings("serial")
+    static class MyPrettyPrinter extends DefaultPrettyPrinter { }
 }