Fix for TAP5-2783

tapestry-hibernate/src/main/java/org/apache/tapestry5/hibernate/web/modules/HibernateModule.java

@@ -102,7 +102,7 @@ public static void contributeValueEncoderSource(
         for (EntityType<?> entityType : entities)
         {
             Class<?> entityClass = entityType.getJavaType();
-            if (entityClass != null)
+            if (entityClass != null && entityType.hasSingleIdAttribute())
             {
                 SingularAttribute<?, ?> id = entityType.getId(entityType.getIdType().getJavaType());
                 final String idenfierPropertyName = id.getName();

tapestry-hibernate/src/test/java/org/example/app0/entities/CompoundIdEntity.java

@@ -0,0 +1,16 @@
+package org.example.app0.entities;
+
+import javax.persistence.Entity;
+import javax.persistence.Id;
+import javax.persistence.IdClass;
+
+/**
+ * This class is an example for an entity that uses a compound id. This triggers a bug with tapestry <= 5.8.6 during
+ * initialisation, see TAP-123.
+ */
+@IdClass(CompoundIdEntityPK.class)
+@Entity
+public class CompoundIdEntity {
+    @Id private Long firstId;
+    @Id private Long secondId;
+}

tapestry-hibernate/src/test/java/org/example/app0/entities/CompoundIdEntityPK.java

@@ -0,0 +1,13 @@
+package org.example.app0.entities;
+
+import java.io.Serializable;
+
+public class CompoundIdEntityPK implements Serializable {
+    private Long firstId;
+    private Long secondId;
+
+    public CompoundIdEntityPK(Long firstId, Long secondId) {
+        this.firstId = firstId;
+        this.secondId = secondId;
+    }
+}