Fix ProxyInstanceImpl#getTableSchemas duplicate schemas

Author: ZorTik

core/src/main/java/me/zort/sqllib/mapping/ProxyInstanceImpl.java

@@ -60,13 +60,15 @@ public Object invoke(Object proxy, Method method, Object[] args) throws Throwabl
 
     @Override
     public List<TableSchema> getTableSchemas(NamingStrategy namingStrategy, boolean sqLite) {
+        List<Class<?>> builtTypes = new ArrayList<>();
         List<TableSchema> schemaList = new ArrayList<>();
         for (Method method : getTypeClass().getDeclaredMethods()) {
             Class<?> resultType = mappingResultAdapter.retrieveResultType(method);
 
-            if (!QueryResult.class.isAssignableFrom(resultType) && statementMapping.isMappingMethod(method)) {
+            if (!QueryResult.class.isAssignableFrom(resultType) && statementMapping.isMappingMethod(method) && !builtTypes.contains(resultType)) {
                 String table = options.getTable() != null ? options.getTable() : Table.Util.getFromContext(method, null);
                 schemaList.add(new EntitySchemaBuilder(table, resultType, namingStrategy, sqLite).buildTableSchema());
+                builtTypes.add(resultType);
             }
         }
         return schemaList;