Map key with AttributeConverter(autoapply=true) doesn't work with enum value

When I have the following mapping:

@ElementCollection
@CollectionTable
@Enumerated(EnumType.STRING)
private Map<LocalDateTime, SomeEnum> map = new HashMap<>();

@Converter(autoApply = true)
public class LocalDateTimeAttributeConverter implements AttributeConverter<LocalDateTime, Timestamp> {...}

Hibernate fails to autoapply the attributeConverter and leave it as binary. So when I execute a query it throws an exception trying to convert to binary
Exception in thread "main" org.hibernate.type.SerializationException: could not deserialize
at org.hibernate.internal.util.SerializationHelper.doDeserialize(SerializationHelper.java:243)
at org.hibernate.internal.util.SerializationHelper.deserialize(SerializationHelper.java:287)
at org.hibernate.type.descriptor.java.SerializableTypeDescriptor.fromBytes(SerializableTypeDescriptor.java:138)
at org.hibernate.type.descriptor.java.SerializableTypeDescriptor.wrap(SerializableTypeDescriptor.java:113)
at org.hibernate.type.descriptor.java.SerializableTypeDescriptor.wrap(SerializableTypeDescriptor.java:27)
at org.hibernate.type.descriptor.sql.VarbinaryTypeDescriptor$2.doExtract(VarbinaryTypeDescriptor.java:53)
at org.hibernate.type.descriptor.sql.BasicExtractor.extract(BasicExtractor.java:47)
at org.hibernate.type.AbstractStandardBasicType.nullSafeGet(AbstractStandardBasicType.java:241)
at org.hibernate.type.AbstractStandardBasicType.nullSafeGet(AbstractStandardBasicType.java:237)
at org.hibernate.type.AbstractStandardBasicType.nullSafeGet(AbstractStandardBasicType.java:227)
at org.hibernate.persister.collection.AbstractCollectionPersister.readIndex(AbstractCollectionPersister.java:839)
at org.hibernate.collection.internal.PersistentMap.readFrom(PersistentMap.java:265)
at org.hibernate.loader.plan.exec.process.internal.CollectionReferenceInitializerImpl.finishUpRow(CollectionReferenceInitializerImpl.java:77)
at org.hibernate.loader.plan.exec.process.internal.AbstractRowReader.readRow(AbstractRowReader.java:108)
at org.hibernate.loader.plan.exec.process.internal.ResultSetProcessorImpl.extractResults(ResultSetProcessorImpl.java:112)
at org.hibernate.loader.plan.exec.internal.AbstractLoadPlanBasedLoader.executeLoad(AbstractLoadPlanBasedLoader.java:121)
at org.hibernate.loader.plan.exec.internal.AbstractLoadPlanBasedLoader.executeLoad(AbstractLoadPlanBasedLoader.java:85)
at org.hibernate.loader.collection.plan.AbstractLoadPlanBasedCollectionInitializer.initialize(AbstractLoadPlanBasedCollectionInitializer.java:82)
at org.hibernate.persister.collection.AbstractCollectionPersister.initialize(AbstractCollectionPersister.java:682)
at org.hibernate.event.internal.DefaultInitializeCollectionEventListener.onInitializeCollection(DefaultInitializeCollectionEventListener.java:75)
at org.hibernate.internal.SessionImpl.initializeCollection(SessionImpl.java:1922)
at org.hibernate.collection.internal.AbstractPersistentCollection$4.doWork(AbstractPersistentCollection.java:546)
at org.hibernate.collection.internal.AbstractPersistentCollection.withTemporarySessionIfNeeded(AbstractPersistentCollection.java:248)
at org.hibernate.collection.internal.AbstractPersistentCollection.initialize(AbstractPersistentCollection.java:542)
at org.hibernate.collection.internal.AbstractPersistentCollection.read(AbstractPersistentCollection.java:133)
at org.hibernate.collection.internal.PersistentMap.toString(PersistentMap.java:250)
at java.lang.String.valueOf(String.java:2994)
at java.io.PrintStream.println(PrintStream.java:821)
at br.com.tecsinapse.jpa.model.Main.main(Main.java:31)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at com.intellij.rt.execution.application.AppMain.main(AppMain.java:144)
Caused by: java.io.StreamCorruptedException: invalid stream header: 32303135
at java.io.ObjectInputStream.readStreamHeader(ObjectInputStream.java:806)
at java.io.ObjectInputStream.<init>(ObjectInputStream.java:299)
at org.hibernate.internal.util.SerializationHelper$CustomObjectInputStream.<init>(SerializationHelper.java:309)
at org.hibernate.internal.util.SerializationHelper$CustomObjectInputStream.<init>(SerializationHelper.java:299)
at org.hibernate.internal.util.SerializationHelper.doDeserialize(SerializationHelper.java:218)
... 33 more