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.

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

javatests/google/registry/xml/XmlTestUtils.java

@@ -139,8 +139,7 @@ public class XmlTestUtils {
         }
         // First, handle all namespace specifications, updating our ns-to-URI map. Use a HashMap
         // rather than an ImmutableMap.Builder so that we can override existing map entries.
-        HashMap<String, String> newNsMap = new HashMap<>();
-        newNsMap.putAll(nsMap);
+        HashMap<String, String> newNsMap = new HashMap<>(nsMap);
         for (String key : namespacesBuilder.build()) {
           // Parse the attribute name, of the form xmlns:nsid, and extract the namespace identifier.
           // If there's no colon, we are setting the default namespace.