There is for this specific JAR file. Instead, it is bundled with the WebSphere installation and must be extracted from an existing environment.
You need this JAR in your project's classpath (e.g., in Eclipse or IntelliJ) to resolve WebSphere-specific management classes. Setting Up the Thin Client Environment
If you have access to a machine where WebSphere Application Server 8.5 is installed, you can find the JAR in the following directories: