Remove dead stores (#797)

* Remove dead stores

* Fix imports

Author: timtebeek

src/main/java/org/openrewrite/staticanalysis/RenameExceptionInEmptyCatch.java

@@ -26,7 +26,6 @@
 import java.time.Duration;
 import java.util.*;
 
-import static java.util.Objects.requireNonNull;
 import static java.util.stream.Collectors.toList;
 
 public class RenameExceptionInEmptyCatch extends Recipe {
@@ -53,7 +52,6 @@ public TreeVisitor<?, ExecutionContext> getVisitor() {
             @Override
             public J visit(@Nullable Tree tree, ExecutionContext ctx) {
                 if (tree instanceof JavaSourceFile) {
-                    JavaSourceFile cu = (JavaSourceFile) requireNonNull(tree);
                     Map<Cursor, Set<String>> variableScopes = new LinkedHashMap<>();
                     getCursor().putMessage("VARIABLES_KEY", variableScopes);
                 }

src/main/java/org/openrewrite/staticanalysis/ReplaceDuplicateStringLiterals.java

@@ -145,8 +145,6 @@ public J visitClassDeclaration(J.ClassDeclaration classDecl, ExecutionContext ct
                     variableNames.add(variableName);
                     entry.getValue().forEach(v -> replacements.put(v, variableName));
                 }
-                duplicateLiteralInfo = null;
-                duplicateLiteralsMap = null;
                 return replacements.isEmpty() ? classDecl :
                         new ReplaceStringLiterals(classDecl, replacements).visitNonNull(classDecl, ctx, requireNonNull(getCursor().getParent()));
             }