Document possible follow-up work

error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/JUnitMethodDeclaration.java

@@ -101,6 +101,8 @@ private void reportMethodRenameBlocker(MethodTree tree, String reason, VisitorSt
             .build());
   }
 
+  // XXX: Consider dropping leading underscores that otherwise result when canonicalizing
+  // `test_some_method_name`.
   private static Optional<String> tryCanonicalizeMethodName(MethodSymbol symbol) {
     return Optional.of(symbol.getQualifiedName().toString())
         .filter(name -> name.startsWith(TEST_PREFIX))

error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/StringJoin.java

@@ -36,7 +36,9 @@
  */
 // XXX: What about `v1 + "sep" + v2` and similar expressions? Do we want to rewrite those to
 // `String.join`, or should some `String.join` invocations be rewritten to use the `+` operator?
-// (The latter suggestion would conflict with the `FormatStringConcatenation` check.)
+// (The latter suggestion would conflict with the `FormatStringConcatenation` check, but does make
+// more sense when `"sep"` is a long string. Similarly for `String.format("%s some long text %s",
+// arg1, arg2)`.)
 @AutoService(BugChecker.class)
 @BugPattern(
     summary = "Prefer `String#join` over `String#format`",