When installing lsp4j and xtend from the current Eclipse release update site (2023-06) It installs lspj4 0.21.0 and xtend 2.31.0
(I started from Eclipse Modeling 2023-06 and then installed lsp4j using the updatesite https://download.eclipse.org/releases/2023-06/ )
A simple project using @JsonRpcData from lsp4j.generator will now fail. The generated java class is incorrect. (the toString
package bug_lsp4j_xtend
import org.eclipse.lsp4j.generator.JsonRpcData
@JsonRpcData
class MyAnnotatedClass {
}
will generate a code that doesn't compile

An equivalent code was working in the previous release I tried (xtend 2.25.0 + lsp4j 0.14.0) (I haven't tried yet to find the exact last working version ...)
project showing the issue joined
bug_lsp4j_xtend_2023-06.zip