--- a/stress-tester/src/main/java/com/passus/st/client/http/filter/HttpFilterMessageWrapper.java	Wed Aug 16 11:59:56 2017 +0200
+++ b/stress-tester/src/main/java/com/passus/st/client/http/filter/HttpFilterMessageWrapper.java	Wed Aug 16 14:56:22 2017 +0200
@@ -36,4 +36,9 @@
     public ByteString getVersion() {
         return message.getVersion();
     }
+
+    public ByteString getHeader(CharSequence name) {
+        HttpHeaders headers = message.getHeaders();
+        return headers.get(name);
+    }
 }

--- a/stress-tester/src/main/java/com/passus/st/client/http/filter/HttpFilterRequestWrapper.java	Wed Aug 16 11:59:56 2017 +0200
+++ b/stress-tester/src/main/java/com/passus/st/client/http/filter/HttpFilterRequestWrapper.java	Wed Aug 16 14:56:22 2017 +0200
@@ -1,7 +1,6 @@
 package com.passus.st.client.http.filter;
 
 import com.passus.data.ByteString;
-import com.passus.net.http.HttpHeaders;
 import com.passus.net.http.HttpRequest;
 import com.passus.net.http.URL;
 import static com.passus.st.client.http.HttpConsts.TAG_SESSION_ID;
@@ -33,9 +32,4 @@
     public String getSessionId() {
         return (String) message.getTag(TAG_SESSION_ID);
     }
-
-    public ByteString getHeader(CharSequence name) {
-        HttpHeaders headers = message.getHeaders();
-        return headers.get(name);
-    }
 }

--- a/stress-tester/src/main/java/com/passus/st/client/http/filter/HttpMessageModificationFilter.java	Wed Aug 16 11:59:56 2017 +0200
+++ b/stress-tester/src/main/java/com/passus/st/client/http/filter/HttpMessageModificationFilter.java	Wed Aug 16 14:56:22 2017 +0200
@@ -53,9 +53,9 @@
         protected final CharSequence extractValue(ValueExtractor extractor, HttpRequest req, HttpResponse resp, HttpFlowContext context) {
             Object value = HttpFiltersUtils.extractValue(extractor, req, resp, context);
             if (value instanceof CharSequence) {
+                LOGGER.debug("extractor={} extracted={}", extractor, value);
                 return (CharSequence) value;
             }
-            LOGGER.debug("extractor={} extracted={}", extractor, value);
 
             return null;
         }

--- a/stress-tester/src/main/java/com/passus/st/client/http/filter/HttpMessagePredicate.java	Wed Aug 16 11:59:56 2017 +0200
+++ b/stress-tester/src/main/java/com/passus/st/client/http/filter/HttpMessagePredicate.java	Wed Aug 16 14:56:22 2017 +0200
@@ -35,4 +35,8 @@
         return predicate.test(wrapper);
     }
 
+    @Override
+    public String toString() {
+        return predicate.toString();
+    }
 }

--- a/stress-tester/src/main/java/com/passus/st/client/http/filter/HttpResponseContentExtractorFilter.java	Wed Aug 16 11:59:56 2017 +0200
+++ b/stress-tester/src/main/java/com/passus/st/client/http/filter/HttpResponseContentExtractorFilter.java	Wed Aug 16 14:56:22 2017 +0200
@@ -76,8 +76,10 @@
 
                 try {
                     String value = contentExtractor.extract(response);
-                    params.set(paramName, value);
-                    LOGGER.debug("Session variable created {}={}", paramName, value);
+                    if (value != null) {
+                        params.set(paramName, value);
+                        LOGGER.debug("Session variable created {}='{}'", paramName, value);
+                    }
                 } catch (IOException ex) {
                     LOGGER.info("Could not read message body", ex);
                 }
@@ -100,8 +102,10 @@
 
             try {
                 String value = contentExtractor.extract(response);
-                params.set(paramName, value);
-                LOGGER.debug("Global variable created {}={}", paramName, value);
+                if (value != null) {
+                    params.set(paramName, value);
+                    LOGGER.debug("Global variable created {}='{}'", paramName, value);
+                }
             } catch (IOException ex) {
                 LOGGER.info("Could not read message body", ex);
             }
@@ -147,6 +151,9 @@
             if (predicate != null) {
                 HttpMessageWrapper wrapper = new HttpMessageWrapper(request, resp, context);
                 exec = predicate.test(wrapper);
+                if (!exec) {
+                    LOGGER.debug("response rejected [{}]: {}", predicate, resp.getHeaders());
+                }
             }
 
             if (exec) {

--- a/stress-tester/src/main/java/com/passus/st/client/http/filter/HttpSessionCookieFilter.java	Wed Aug 16 11:59:56 2017 +0200
+++ b/stress-tester/src/main/java/com/passus/st/client/http/filter/HttpSessionCookieFilter.java	Wed Aug 16 14:56:22 2017 +0200
@@ -139,8 +139,8 @@
         HttpCookie requestCookie = findSessionCookie(modifiedRequest);
         HttpCookie inCookie = findSessionCookie(context.origReponse());
 
-        String oldLiveSessionId = null;
         if (inCookie != null) {
+            String oldLiveSessionId = null;
             if (requestCookie != null) {
                 oldLiveSessionId = requestCookie.getValue().toString();
                 ParametersBag session = context.scopes().getSession(oldLiveSessionId);
@@ -148,7 +148,7 @@
             }
             makeMappingTagsAndSession(modifiedRequest, realResponse, context, inCookie, oldLiveSessionId);
         } else if (requestCookie != null) {
-            makeMappingTagsAndSession(modifiedRequest, realResponse, context, requestCookie, oldLiveSessionId);
+            makeMappingTagsAndSession(modifiedRequest, realResponse, context, requestCookie, null);
         } else {
             Object sessionId = modifiedRequest.getTag(TAG_SESSION_ID);
             if (sessionId != null) {