keep allOf, anyOf, oneOf alongside properties while flattening

Author: frantuma

modules/swagger-parser-v3/src/main/java/io/swagger/v3/parser/util/InlineModelResolver.java

@@ -680,6 +680,11 @@ public Schema createModelFromProperty(Schema schema, String path) {
                 flattenProperties(properties, path);
                 model.setProperties(properties);
             }
+            if (schema instanceof ComposedSchema){
+                model.setAllOf(((ComposedSchema) schema).getAllOf());
+                model.setAnyOf(((ComposedSchema) schema).getAnyOf());
+                model.setOneOf(((ComposedSchema) schema).getOneOf());
+            }
 
             return model;
         }