Supply a ToStringBuilder in common location

When the dependency on xbase.lib was removed in eclipse-lsp4j#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 eclipse-lsp4j#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.
+    * 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»