Supply a ToStringBuilder in common location

When the dependency on xbase.lib was removed in #529 it put the
implicit requirement that there is a class called ToStringBuilder
in a sub-package of the xtend class called `util`.

This change provides the ToStringBuilder in an util package
in the org.eclipse.lsp4j.jsonrpc bundle so that consumers
of LSP4J do not need to copy ToStringBuilder into their
own source code.

Fixes #742

CHANGELOG.md

@@ -11,6 +11,10 @@ Breaking API changes:
     * See [#768](https://github.com/eclipse-lsp4j/lsp4j/issues/768) for detailed discussion.
   * The name field in WorkspaceFolder is no longer optional according to the specification.
     * See [#741](https://github.com/eclipse-lsp4j/lsp4j/issues/741) for detailed discussion.
+  * The LSP4J generator when applied to `@JsonRpcData` annotated classes generates a dependency on package `org.eclipse.lsp4j.jsonrpc.util` in the `org.eclipse.lsp4j.jsonrpc` bundle to provide an implementation of `ToStringBuilder`.
+    * This removes the implied requirement in LSP4J 0.21.0 that there is a class called `ToStringBuilder` in a sub-package called `util`.
+    * This also removes the duplicated class `ToStringBuilder` in packages `org.eclipse.lsp4j.debug.util` and `org.eclipse.lsp4j.util`.
+    * See [#742](https://github.com/eclipse-lsp4j/lsp4j/issues/742) for detailed discussion.
 
 Nightly japicmp report: <https://download.eclipse.org/lsp4j/builds/main/japicmp-report/>
 

org.eclipse.lsp4j.generator/src/main/java/org/eclipse/lsp4j/generator/JsonRpcDataProcessor.xtend

@@ -159,10 +159,7 @@ class JsonRpcDataProcessor extends AbstractClassProcessor {
 			returnType = string
 			addAnnotation(newAnnotationReference(Override))
 			val accessorsUtil = new AccessorsProcessor.Util(context)
-			val fqn = impl.qualifiedName
-			val char dot = '.'
-			val pkg = fqn.substring(0, fqn.lastIndexOf(dot))
-			val toStringBuilderClassName = (pkg+".util.ToStringBuilder")
+			val toStringBuilderClassName = ("org.eclipse.lsp4j.jsonrpc.util.ToStringBuilder")
 			body = '''
 				«toStringBuilderClassName.newTypeReference()» b = new «toStringBuilderClassName.newTypeReference()»(this);
 				«FOR field : toStringFields»