Creation of Temporary File in Directory with Insecure Permissions in the OpenAPI Generator Maven plugin

OpenAPI Generator allows generation of API client libraries, server stubs, documentation and configuration automatically given an OpenAPI Spec. Using `File.createTempFile` in JDK will result in creating and using insecure temporary files that can leave application and system data vulnerable to attacks. OpenAPI Generator maven plug-in creates insecure temporary files during the process. The issue has been patched with `Files.createTempFile` and released in the v5.1.0 stable version.