This open source plugin can create class diagram in Visual Paradigm programmatically using the Open API. https://www.visual-paradigm.com/guide/uml-unified-modeling-language/what-is-class-diagram/
Details about how to deploy this plugin to Visual Paradigm can be found at https://knowhow.visual-paradigm.com/openapi/how-to-deploy-plugins-to-vp-application/
More details about Visual Paradigm's Open API can be found at
Plugin User's Guide http://www.visual-paradigm.com/support/documents/pluginuserguide.jsp
Know-how pages on Open API https://knowhow.visual-paradigm.com/category/openapi/
Javadoc http://www.visual-paradigm.com/support/documents/pluginapi.jsp