Fix NPE in ModelUtils.isFreeFormObject() (OpenAPITools#1625)

Fixes OpenAPITools#1696 An object schema containing no properties that also has additionalProperties set to an object schema with no properties will cause ModelUtils.isFreeFormObject to throw an NPE. This PR adds additional checking to avoid the NPE.
sruehl · Dec 7, 2018 · 2d39f14 · 2d39f14
1 parent 2f4bea6
commit 2d39f14
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Showing 2 changed files with 37 additions and 12 deletions.
diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/utils/ModelUtils.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/utils/ModelUtils.java
@@ -547,20 +547,17 @@ public static boolean isFreeFormObject(Schema schema) {
         if ("object".equals(schema.getType())) {
             // no properties
             if ((schema.getProperties() == null || schema.getProperties().isEmpty())) {
-                if (schema.getAdditionalProperties() == null) {
+                Schema addlProps = getAdditionalProperties(schema);
+                // additionalProperties not defined
+                if (addlProps == null) {
                     return true;
                 } else {
-                    // additionalProperties set to true
-                    if (schema.getAdditionalProperties() instanceof Boolean
-                            && (Boolean) schema.getAdditionalProperties()) {
-                        return true;
-                    }
-
-                    // additionalProperties is set to {}
-                    if (schema.getAdditionalProperties() instanceof Schema && schema.getAdditionalProperties() != null
-                            && schema.getAdditionalProperties() instanceof ObjectSchema
-                            && ((Schema) schema.getAdditionalProperties()).getProperties().isEmpty()) {
-                        return true;
+                    if (addlProps instanceof ObjectSchema) {
+                        ObjectSchema objSchema = (ObjectSchema) addlProps;
+                        // additionalProperties defined as {}
+                        if (objSchema.getProperties() == null || objSchema.getProperties().isEmpty()) {
+                            return true;
+                        }
                     }
                 }
             }

diff --git a/modules/openapi-generator/src/test/java/org/openapitools/codegen/utils/ModelUtilsTest.java b/modules/openapi-generator/src/test/java/org/openapitools/codegen/utils/ModelUtilsTest.java
@@ -199,4 +199,32 @@ public void testComposedSchemasAreNotUnaliased() {
 
         Assert.assertEquals(refToComposedSchema, ModelUtils.unaliasSchema(allSchemas, refToComposedSchema));
     }
+
+    /**
+     * Issue https://github.com/OpenAPITools/openapi-generator/issues/1624.
+     * ModelUtils.isFreeFormObject() should not throw an NPE when passed an empty
+     * object schema that has additionalProperties defined as an empty object schema.
+     */
+    @Test
+    public void testIsFreeFormObject() {
+        // Create initial "empty" object schema.
+        ObjectSchema objSchema = new ObjectSchema();
+        Assert.assertTrue(ModelUtils.isFreeFormObject(objSchema));
+
+        // Set additionalProperties to an empty ObjectSchema.
+        objSchema.setAdditionalProperties(new ObjectSchema());
+        Assert.assertTrue(ModelUtils.isFreeFormObject(objSchema));
+
+        // Add a single property to the schema (no longer a free-form object).
+        Map<String, Schema> props = new HashMap<>();
+        props.put("prop1", new StringSchema());
+        objSchema.setProperties(props);
+        Assert.assertFalse(ModelUtils.isFreeFormObject(objSchema));
+
+        // Test a non-object schema
+        Assert.assertFalse(ModelUtils.isFreeFormObject(new StringSchema()));
+
+        // Test a null schema
+        Assert.assertFalse(ModelUtils.isFreeFormObject(null));
+    }
 }