move MDCHelper to org.slf4j

Signed-off-by: Ceki Gulcu <ceki@qos.ch>

slf4j-api/src/main/java/org/slf4j/MDCHelper.java

@@ -0,0 +1,39 @@
+package org.slf4j;
+
+import java.util.HashSet;
+import java.util.Set;
+
+public class MDCHelper  {
+
+
+    Set<String> keySet = new HashSet();
+
+    public MDCHelper() {
+
+    }
+
+    public MDCHelper put(String key, String value) {
+        MDC.put(key, value);
+        keySet.add(key);
+        return this;
+    }
+
+    public MDCHelper addKey(String key) {
+        keySet.add(key);
+        return this;
+    }
+
+    public MDCHelper addKeys(String... keys) {
+        for(String k: keys) {
+            keySet.add(k);
+        }
+        return this;
+    }
+
+
+    public void removeSet() {
+        for(String key: keySet) {
+            MDC.remove(key);
+        }
+    }
+}

slf4j-api/src/test/java/org/slf4j/MDCHelperTest.java

@@ -0,0 +1,15 @@
+package org.slf4j;
+
+import org.junit.Test;
+
+public class MDCHelperTest {
+
+
+    @Test
+    public void smoke() {
+        MDCHelper mdch = new MDCHelper();
+
+        //mdch.addKey()
+
+    }
+}