Metadata: Fix Javadoc warning

Javadoc warns:

  "javadoc malformed reference (missing end space separator)"

Removing the type specifier fixes it.

Change-Id: Ie3d8b994f801604080f622cc09035cae3ed43f87
diff --git a/java/com/google/gerrit/server/logging/Metadata.java b/java/com/google/gerrit/server/logging/Metadata.java
index c3df289..4defded 100644
--- a/java/com/google/gerrit/server/logging/Metadata.java
+++ b/java/com/google/gerrit/server/logging/Metadata.java
@@ -145,7 +145,7 @@
 
   /**
    * Returns a string representation of this instance that is suitable for logging. This is wrapped
-   * in a {@link LazyArg<String>} because it is expensive to evaluate.
+   * in a {@link LazyArg} because it is expensive to evaluate.
    *
    * <p>{@link #toString()} formats the {@link Optional} fields as {@code key=Optional[value]} or
    * {@code key=Optional.empty}. Since this class has many optional fields from which usually only a