added interface for composed schema handler implementation

Author: HugoMario

modules/swagger-codegen/src/main/java/io/swagger/codegen/v3/ISchemaHandler.java

@@ -0,0 +1,13 @@
+package io.swagger.codegen.v3;
+
+import io.swagger.v3.oas.models.media.Schema;
+
+public interface ISchemaHandler {
+
+    /**
+     * check if there is any composed schema in models or properties. And create codegen model objects if it's required.
+     * @param codegenModel
+     * @param schema
+     */
+    void proccessComposedSchemas(CodegenModel codegenModel, Schema schema);
+}