[java] TooFewBranchesForSwitch: report empty switch

This fixes a false negative

pmd-java/src/main/resources/category/java/performance.xml

@@ -631,7 +631,7 @@ Note: This rule was named TooFewBranchesForASwitchStatement before PMD 7.7.0.
 //(SwitchStatement | SwitchExpression)
   [ (count(*) - 1) < $minimumNumberCaseForASwitch ]
   (: only consider if no pattern matching is used :)
-  [*/SwitchLabel[@PatternLabel = false()]]
+  [not(*/SwitchLabel[@PatternLabel = true()])]
 ]]>
                 </value>
             </property>

pmd-java/src/test/resources/net/sourceforge/pmd/lang/java/rule/performance/xml/TooFewBranchesForSwitch.xml

@@ -4,6 +4,19 @@
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xsi:schemaLocation="http://pmd.sourceforge.net/rule-tests http://pmd.sourceforge.net/rule-tests_1_0_0.xsd">
 
+    <test-code>
+        <description>Switch Statement with no case, not ok</description>
+        <rule-property name="minimumNumberCaseForASwitch">3</rule-property>
+        <expected-problems>1</expected-problems>
+        <code><![CDATA[
+public class DumbSwitch {
+    public void foo(int i) {
+        switch (i) { }
+    }
+}
+        ]]></code>
+    </test-code>
+
     <test-code>
         <description>Switch Statement with only one case, not ok</description>
         <rule-property name="minimumNumberCaseForASwitch">3</rule-property>