[CALCITE-3067] Splunk adapter cannot parse right session keys from Sp…

…lunk 7.2 (Shawn Chen)

Close apache#1222

splunk/src/main/java/org/apache/calcite/adapter/splunk/search/SplunkConnectionImpl.java

@@ -58,7 +58,7 @@ public class SplunkConnectionImpl implements SplunkConnection {
 
   private static final Pattern SESSION_KEY =
       Pattern.compile(
-          "<response>\\s*<sessionKey>([0-9a-f]+)</sessionKey>\\s*</response>");
+          "<sessionKey>([0-9a-zA-Z^_]+)</sessionKey>");
 
   final URL url;
   final String username;