Fix some issues caught by IntelliJ static code analysis

The most common issues were:
* Arrays.asList() shouldn't be called with a single parameter.
* Broken Javadoc @links.
* Unnecessary casts and type declarations.
* Unnecessary unused variable initializations.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=230994311

javatests/google/registry/export/sheet/SheetSynchronizerTest.java

@@ -84,9 +84,7 @@ public class SheetSynchronizerTest {
 
   // Explicitly constructs a List<Object> to avoid newArrayList typing to ArrayList<String>
   private List<Object> createRow(Object... elements) {
-    List<Object> row = new ArrayList<>();
-    row.addAll(Arrays.asList(elements));
-    return row;
+    return new ArrayList<>(Arrays.asList(elements));
   }
 
   @Test