fix: look for cross-referenced fields in Java

.grit/patterns/java/unused_private_fields.md

@@ -7,15 +7,14 @@ tags: [java]
 
 Unused private fields constitute dead code and should therefore be removed.
 
-
 ```grit
 language java
 
 class_body($declarations) where {
     $declarations <: contains bubble($declarations) {
         field_declaration($modifiers) as $field where {
             $field <: contains variable_declarator($name) where {
-                $declarations <: not contains $name until field_declaration(),
+                $declarations <: not contains $name until $field,
                 $name <: not or {
                     `serialVersionUID`,
                     `serialPersistentFields`,
@@ -81,3 +80,34 @@ public class MyClass {
   private native static void doSomethingNative();
 }
 ```
+
+## Does not remove fields used in other fields
+
+```java
+public class Test {
+
+    private static final String HELLO = "Hello, ";
+    private static final String WORLD = "World";
+
+    private static final String HELLO_WORLD = HELLO + WORLD;
+    private static final String REMOVE_THIS = "Remove this";
+
+    public static void main(String[] args) {
+        System.out.println(HELLO_WORLD);
+    }
+}
+```
+
+```java
+public class Test {
+
+    private static final String HELLO = "Hello, ";
+    private static final String WORLD = "World";
+
+    private static final String HELLO_WORLD = HELLO + WORLD;
+
+    public static void main(String[] args) {
+        System.out.println(HELLO_WORLD);
+    }
+}
+```