Update exception variable names

Consistently use `ex` for caught exception and `cause` for Exception
constructor arguments.

Issue gh-8945

cas/src/main/java/org/springframework/security/cas/authentication/CasAuthenticationProvider.java

@@ -156,8 +156,8 @@ public class CasAuthenticationProvider implements AuthenticationProvider, Initia
 			return new CasAuthenticationToken(this.key, userDetails, authentication.getCredentials(),
 					this.authoritiesMapper.mapAuthorities(userDetails.getAuthorities()), userDetails, assertion);
 		}
-		catch (final TicketValidationException e) {
-			throw new BadCredentialsException(e.getMessage(), e);
+		catch (TicketValidationException ex) {
+			throw new BadCredentialsException(ex.getMessage(), ex);
 		}
 	}
 

cas/src/main/java/org/springframework/security/cas/web/authentication/ServiceAuthenticationDetailsSource.java

@@ -74,8 +74,8 @@ public class ServiceAuthenticationDetailsSource
 			return new DefaultServiceAuthenticationDetails(this.serviceProperties.getService(), context,
 					this.artifactPattern);
 		}
-		catch (MalformedURLException e) {
-			throw new RuntimeException(e);
+		catch (MalformedURLException ex) {
+			throw new RuntimeException(ex);
 		}
 	}