spotbugs: suppress USBR on equals/hashCode/canEqual/toString (Lombok)

Lombok-generated equals / hashCode / canEqual / toString carry the
textbook polynomial-hash pattern (int result = 1; result = result * 59
+ ...; return result;) which fb-contrib's USBR detector reads at the
bytecode level as a store-then-immediate-return.

SpotBugs core already skips its own detectors on members carrying
@lombok.Generated (emitted by lombok.config's
lombok.addLombokGeneratedAnnotation = true), but fb-contrib runs as a
separate plugin family and does not honour that annotation. A method-
name-based <Match> covers every member Lombok can emit.

Clears 18 jllama findings at SpotBugs Max+Low. The collateral cost is
small: any handwritten equals/hashCode/toString that genuinely
stores-then-immediately-returns is either a debugger-friendly local-
variable pattern or a micro-optimisation, both intentional here.

https://claude.ai/code/session_01LzoKmqzgtQsELS5tsH4Wog

Author: claude

spotbugs-exclude.xml

@@ -173,4 +173,36 @@ SPDX-License-Identifier: MIT
         <Method name="&lt;init&gt;"/>
     </Match>
 
+    <!--
+        USBR_UNNECESSARY_STORE_BEFORE_RETURN on Lombok-generated equals / hashCode /
+        canEqual / toString.
+
+        Lombok's @EqualsAndHashCode and @ToString annotation processors inject the
+        textbook polynomial-hash bytecode pattern (and lombok.config already emits
+        @lombok.Generated on every synthetic member via
+        lombok.addLombokGeneratedAnnotation = true):
+
+            int result = 1;
+            result = result * 59 + ($field == null ? 43 : $field.hashCode());
+            ...
+            return result;          // USBR fires here, on the istore_N / iload_N / ireturn triplet
+
+        SpotBugs core honours @lombok.Generated and skips its own detectors on those
+        members, but the fb-contrib plugin's USBR detector does NOT &#x2014; fb-contrib
+        is a separate plugin family with its own filter pipeline. Suppressing USBR on
+        equals / hashCode / canEqual / toString matches every method name Lombok can
+        emit. The collateral cost is small: any handwritten member of those four names
+        that genuinely stores-then-immediately-returns is either a debugger-friendly
+        local-variable pattern or a micro-optimisation, both intentional here.
+    -->
+    <Match>
+        <Or>
+            <Method name="equals"/>
+            <Method name="hashCode"/>
+            <Method name="canEqual"/>
+            <Method name="toString"/>
+        </Or>
+        <Bug pattern="USBR_UNNECESSARY_STORE_BEFORE_RETURN"/>
+    </Match>
+
 </FindBugsFilter>