check for repeated logical subtype names FasterXML#3500

Author: ancane

src/main/java/com/fasterxml/jackson/databind/introspect/JacksonAnnotationIntrospector.java

@@ -621,14 +621,47 @@ public List<NamedType> findSubtypes(Annotated a)
         JsonSubTypes t = _findAnnotation(a, JsonSubTypes.class);
         if (t == null) return null;
         JsonSubTypes.Type[] types = t.value();
+
+        if (t.allowRepeatedNames()) {
+            ArrayList<NamedType> result = new ArrayList<NamedType>(types.length);
+            for (JsonSubTypes.Type type : types) {
+                result.add(new NamedType(type.value(), type.name()));
+                // [databind#2761]: alternative set of names to use
+                for (String name : type.names()) {
+                    result.add(new NamedType(type.value(), name));
+                }
+            }
+            return result;
+        } else {
+            return findSubtypesCheckRepeatedNames(a.getName(), types);
+        }
+    }
+
+    private List<NamedType> findSubtypesCheckRepeatedNames(String annotatedTypeName, JsonSubTypes.Type[] types)
+    {
         ArrayList<NamedType> result = new ArrayList<NamedType>(types.length);
+        Set<String> seenNames = new HashSet<>();
         for (JsonSubTypes.Type type : types) {
             result.add(new NamedType(type.value(), type.name()));
+
+            if (!type.name().isEmpty() && seenNames.contains(type.name())) {
+                throw new IllegalArgumentException("Annotated type [" + annotatedTypeName + "] got repeated subtype name [" + type.name() + "]");
+            } else {
+                seenNames.add(type.name());
+            }
+
             // [databind#2761]: alternative set of names to use
             for (String name : type.names()) {
                 result.add(new NamedType(type.value(), name));
+
+                if (!name.isEmpty() && seenNames.contains(name)) {
+                    throw new IllegalArgumentException("Annotated type [" + annotatedTypeName + "] got repeated subtype name [" + name + "]");
+                } else {
+                    seenNames.add(name);
+                }
             }
         }
+
         return result;
     }
 

src/test/java/com/fasterxml/jackson/databind/jsontype/TestMultipleTypeNames.java

@@ -5,6 +5,7 @@
 
 import com.fasterxml.jackson.databind.BaseMapTest;
 import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.exc.InvalidDefinitionException;
 import com.fasterxml.jackson.databind.exc.UnrecognizedPropertyException;
 
 import java.util.List;
@@ -72,6 +73,28 @@ static class BaseForNameAndNamesTest {
         public MultiTypeName getData() { return data; }
     }
 
+    static class WrapperForNotUniqueNamesTest {
+        List<BaseForNotUniqueNamesTest> base;
+        public List<BaseForNotUniqueNamesTest> getBase() { return base; }
+    }
+
+    static class BaseForNotUniqueNamesTest {
+        private String type;
+        public String getType() { return type; }
+
+        @JsonTypeInfo(
+                use = JsonTypeInfo.Id.NAME,
+                include = JsonTypeInfo.As.EXTERNAL_PROPERTY,
+                property = "type"
+        )
+        @JsonSubTypes(value = {
+                @JsonSubTypes.Type(value = A.class, name = "a"),
+                @JsonSubTypes.Type(value = B.class, names = {"b","a"}),
+        }, allowRepeatedNames = false)
+        MultiTypeName data;
+        public MultiTypeName getData() { return data; }
+    }
+
     /*
     /**********************************************************
     /* Test methods
@@ -133,4 +156,17 @@ public void testNameAndNames() throws Exception
             verifyException(e, "Unrecognized field \"data\"");
         }
     }
+
+    public void testNotUniqueNameAndNames() throws Exception
+    {
+        String json = "{\"base\": [{\"type\":\"a\", \"data\": {\"x\": 5}}, {\"type\":\"b\", \"data\": {\"y\": 3.1}}, {\"type\":\"c\", \"data\": {\"y\": 33.8}}]}";
+
+        try  {
+            MAPPER.readValue(json, WrapperForNotUniqueNamesTest.class);
+            fail("This serialisation should fail because of repeated subtype name");
+        } catch (InvalidDefinitionException e) {
+            verifyException(e, "Annotated type [data] got repeated subtype name [a]");
+        }
+    }
+
 }