finagle-core: Remove Unused SSL/TLS Exceptions

Problem / Solution

finagle-core contains two legacy SSL/TLS exceptions which are no longer
used, `SslHandshakeException` and `SslHostVerificationException`. Since
they are no longer used, they should be removed.

JIRA Issues: CSL-8347

Differential Revision: https://phabricator.twitter.biz/D330138

CHANGELOG.rst

@@ -97,6 +97,10 @@ Bug Fixes
 Breaking API Changes
 ~~~~~~~~~~~~~~~~~~~~
 
+* finagle-core: The exceptions `c.t.f.SslHandshakeException` and
+  `c.t.f.SslHostVerificationException` were no longer used and have
+  been removed. ``PHAB_ID=D330138``
+
 * finagle-mysql: The structure of `c.t.f.mysql.Request` has changed. It is now based on
   a higher level `c.t.f.mysql.ProtocolMessage` and the `cmd` field must contain a value.
   Additionally, the synthetic `Command.COM_NO_OP` has been removed, as due to the

finagle-core/src/main/scala/com/twitter/finagle/Exceptions.scala

@@ -515,29 +515,6 @@ case class SslVerificationFailedException(ex: Option[Throwable], remoteAddr: Opt
   def underlying: Throwable = ex.orNull
 }
 
-/**
- * Indicates that an error occurred while an SSL handshake was being performed
- * with a server at a given `remoteAddress`.
- */
-case class SslHandshakeException(ex: Option[Throwable], remoteAddr: Option[SocketAddress])
-    extends SslException(ex, remoteAddr) {
-  def this(underlying: Throwable, remoteAddress: SocketAddress) =
-    this(Option(underlying), Option(remoteAddress))
-  def this() = this(None, None)
-
-  /**
-   * The cause of this exception, or `null` if there is no cause.
-   */
-  def underlying: Throwable = ex.orNull
-}
-
-/**
- * Indicates that the certificate for a given session was invalidated.
- */
-case class SslHostVerificationException(principal: String) extends SslException(None, None) {
-  def this() = this(null)
-}
-
 /**
  * Indicates that connecting to a given `remoteAddress` was refused.
  */