Add test verifying no malformed wildcards result from captured type variables with a Collection<? extends ...> type

java/ql/test/library-tests/wildcards-and-captured-types/Test.java

@@ -0,0 +1,13 @@
+import java.util.Collection;
+
+public class Test {
+
+  public Collection<? extends CharSequence> getCollection() {
+    return null;
+  }
+
+  public void test() {
+    this.getCollection().isEmpty();
+  }
+
+}

java/ql/test/library-tests/wildcards-and-captured-types/test.ql

@@ -0,0 +1,5 @@
+import java
+
+from Method m, Type t
+where m.getAParamType() = t and t.toString().matches("%? super ? extends%")
+select m, t