util-validator: Unmangling more names in ScalaValidator

Problem

When merging in Felix's upgrade patch, I broke a unit test by trying
to unmangle in a too-narrow way, and missed it through negligence.

Solution

Unmangle appropriately, the way the original commit worked!

JIRA Issues: CSL-11030

Differential Revision: https://phabricator.twitter.biz/D684906

util-validator/src/main/scala/com/twitter/util/validation/ScalaValidator.scala

@@ -860,15 +860,15 @@ class ScalaValidator private[validation] (
  val results = new mutable.ListBuffer[ConstraintViolation[T]]()
  val parameters: Array[Parameter] = executableDescriptor.executable.getParameters
  val parameterNamesList: Array[String] =
- parameterNames match {
+ (parameterNames match {
  case Some(names) =>
  names
  case _ =>
- getExecutableParameterNames(executableDescriptor.executable).map { maybeMangled =>
-  DescriptorFactory.unmangleName(
-  maybeMangled
-  ) // parameter names are encoded since Scala 2.13.5
-  }
+ getExecutableParameterNames(executableDescriptor.executable)
+ }).map { maybeMangled =>
+ DescriptorFactory.unmangleName(
+ maybeMangled
+ ) // parameter names are encoded since Scala 2.13.5
  }
 
  // executable parameter constraints