Additional resource parsing (WIP)

[fabapp2]

Currently, it is possible to define specialized resources, EjbJarXml is an example.
These resources might not use the parsing result created by OpenRewrite but a custom representation like a JAXB-generated object model.

Current implementation

• ProjectContextInitializer scans the given project dir
• The scanned resources are parsed by MavenProjectParser and wrapped in RewriteSourceFileHoldes
• The RewriteSourceFileHoldes are added to the ProjectResourceSet
• ProjectContextInitializer then calls applyProjectResourceWrappers(ProjectResourceSet)
• Another loop over all resources in ProjectResourceSet trying to find a matching ProjectResourceWrapper to replace RewriteSourceFileHolder with a more "speciaized resource", e.g. EjbJarXml (which inherits from RewriteSourceFileHolder)

Problems with this implementation

• All resources get parsed by OpenRewrite (currently in MavenProjectParser) and in case a ProjectResourceWrapper is found it "parses" the resource again, e.g. by parsing the XML file with JAXB. => All specialized resources are parsed twice
• Because of this implementation two models of a resource exist in parallel. In the given example OpenRewrite created an Xml.Document after parsing the JAXB model representation is kept in a separate variable. => This allows for concurrent modifications and wastes memory
• Some specialized resources might require access to other resources, e.g. Java classes to provide a complete API. Think of a representation of SpringBootRestController