Add empty-inline-tag.ql

Author: Marcono1234

codeql-custom-queries-java/queries/javadoc/empty-inline-tag.ql

@@ -0,0 +1,33 @@
+/**
+ * Finds empty Javadoc inline tags for tags which normally expect a value, e.g. `{@code}`.
+ * In that case the empty inline tag has no effect (except for `{@value}` on fields), so most
+ * likely the inline tag in the documentation comment is empty by accident.
+ * 
+ * @kind problem
+ */
+
+import java
+
+from JavadocText javadocText, string tagName, string inlineTag
+where
+    // Note: For some tags such as {@index} javadoc command displays an error
+    (
+        tagName = [
+            "code",
+            "index",
+            "link",
+            "linkplain",
+            "literal",
+            "summary",
+            "systemProperty"
+        ]
+        or
+        // {@value} is allowed for fields
+        tagName = "value"
+        and not exists(Javadoc javadoc |
+            javadoc = javadocText.getJavadoc()
+            and javadoc.getCommentedElement() instanceof Field
+        )
+    )
+    and inlineTag = javadocText.getText().regexpFind("\\{@" + tagName + "\\s*\\}", _, _)
+select javadocText, "Contains empty inline tag: " + inlineTag