Apply suggestions from code review

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

Author: timo-a

src/main/java/org/openrewrite/java/migrate/lombok/ConvertGetter.java

@@ -18,6 +18,7 @@
 import lombok.AccessLevel;
 import lombok.EqualsAndHashCode;
 import lombok.Value;
+import org.jspecify.annotations.Nullable;
 import org.openrewrite.ExecutionContext;
 import org.openrewrite.Recipe;
 import org.openrewrite.TreeVisitor;
@@ -91,7 +92,7 @@ public J.ClassDeclaration visitClassDeclaration(J.ClassDeclaration classDecl, Ex
         }
 
         @Override
-        public J.MethodDeclaration visitMethodDeclaration(J.MethodDeclaration method, ExecutionContext ctx) {
+        public @Nullable J.MethodDeclaration visitMethodDeclaration(J.MethodDeclaration method, ExecutionContext ctx) {
             assert method.getMethodType() != null;
 
             if (LombokUtils.isEffectivelyGetter(method)) {

src/main/java/org/openrewrite/java/migrate/lombok/LombokUtils.java

@@ -42,8 +42,7 @@ public static boolean isEffectivelyGetter(J.MethodDeclaration method) {
             if (returnExpression instanceof J.Identifier) {
                 J.Identifier identifier = (J.Identifier) returnExpression;
                 JavaType.Variable fieldType = identifier.getFieldType();
-                boolean typeMatch = method.getType().equals(fieldType.getType());
-                return typeMatch;
+                return method.getType().equals(fieldType.getType());
             }
         }
         return false;