Add failing test for #2440

pmd-java/src/test/resources/net/sourceforge/pmd/lang/java/rule/design/xml/FinalFieldCouldBeStatic.xml

@@ -278,4 +278,13 @@ public class Test {
 ]]></code>
     </test-code>
 
+    <test-code>
+        <description>FN when the right side of the assignment is a constant expression #2440</description>
+        <expected-problems>1</expected-problems>
+        <code><![CDATA[
+public class Test {
+    private final double HALF_PI = Math.PI * 0.5; // false-negative
+}
+]]></code>
+    </test-code>
 </test-data>