Fixes #5063: generate distinct names (type ids) if Version has no artifact id

release-notes/VERSION-2.x

@@ -83,6 +83,8 @@ Project: jackson-databind
  (contributed by @pjfanning)
 #5052: Minor bug in `FirstCharBasedValidator.forFirstNameRule()`: returns `null`
   in non-default case
+#5063: `SimpleModule` not registered due to `getTypeId()` returning an empty string
+ (reported by @seadbrane)
 #5069: Add copy-constructor for `MappingIterator`
  (contributed by @wrongwrong)
 

src/main/java/com/fasterxml/jackson/databind/module/SimpleModule.java

@@ -130,14 +130,19 @@ public SimpleModule() {
         // note: generate different name for direct instantiation, sub-classing;
         // this to avoid collision in former case while still addressing
         // [databind#3110]
-        _name = (getClass() == SimpleModule.class)
-                ? "SimpleModule-"+MODULE_ID_SEQ.getAndIncrement()
-                : getClass().getName();
+        _name = _generateName(getClass());
         _version = Version.unknownVersion();
         // 07-Jun-2021, tatu: [databind#3110] Not passed explicitly so...
         _hasExplicitName = false;
     }
 
+    // @since 2.19
+    private static String _generateName(Class<?> cls) {
+        return (cls == SimpleModule.class)
+                ? "SimpleModule-"+MODULE_ID_SEQ.getAndIncrement()
+                : cls.getName();
+    }
+
     /**
      * Convenience constructor that will default version to
      * {@link Version#unknownVersion()}.
@@ -148,10 +153,21 @@ public SimpleModule(String name) {
 
     /**
      * Convenience constructor that will use specified Version,
-     * including name from {@link Version#getArtifactId()}.
+     * including name from {@link Version#getArtifactId()}
+     * (if available -- if not, will generate).
      */
     public SimpleModule(Version version) {
-        this(version.getArtifactId(), version);
+        // 07-Apr-2025, tatu: [databind#5063]: check that we actually have a name;
+        //    if not, generate it
+        String maybeName = version.getArtifactId();
+        // Only considered explicit if name is non-null and not empty (i.e. not generated)
+        _hasExplicitName = (maybeName != null) && !maybeName.isEmpty();
+        if (_hasExplicitName) {
+            _name = maybeName;
+        } else {
+            _name = _generateName(getClass());
+        }
+        _version = Version.unknownVersion();
     }
 
     /**

src/test/java/com/fasterxml/jackson/databind/module/SimpleModuleTest.java

@@ -235,6 +235,19 @@ public void serialize(Test3787Bean value, JsonGenerator gen, SerializerProvider
         }
     }
 
+    // For [databind#5063]
+    static class Module5063A extends SimpleModule {
+        public Module5063A() {
+            super(Version.unknownVersion());
+        }
+    }
+
+    static class Module5063B extends SimpleModule {
+        public Module5063B() {
+            super(Version.unknownVersion());
+        }
+    }
+
     /*
     /**********************************************************
     /* Unit tests; first, verifying need for custom handlers
@@ -624,4 +637,15 @@ public void testAddModuleWithDeserializerTwiceThenOnlyLatestIsKept_reverseOrder(
 
         assertEquals("I am A", result.value);
     }
+
+    // For [databind#5063]
+    @Test
+    public void testDuplicateModules5063() {
+        ObjectMapper mapper = JsonMapper.builder()
+                .addModule(new Module5063A())
+                .addModule(new Module5063B())
+                .build();
+        Set<Object> modules = mapper.getRegisteredModuleIds();
+        assertEquals(2, modules.size());
+    }
 }