FELIX-5107: NullPointerException in org.apache.felix.eventadmin.impl.adapter.LogEventAdapter if log msg is empty

Patch applied on behalf of Torsten Mielke, submitted via Gitub, with many thanks.
This closes #40


git-svn-id: https://svn.apache.org/repos/asf/felix/trunk@1714987 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/eventadmin/impl/src/main/java/org/apache/felix/eventadmin/impl/adapter/LogEventAdapter.java b/eventadmin/impl/src/main/java/org/apache/felix/eventadmin/impl/adapter/LogEventAdapter.java
index 31df557..7cce20e 100644
--- a/eventadmin/impl/src/main/java/org/apache/felix/eventadmin/impl/adapter/LogEventAdapter.java
+++ b/eventadmin/impl/src/main/java/org/apache/felix/eventadmin/impl/adapter/LogEventAdapter.java
@@ -177,7 +177,8 @@
 
                     properties.put("log.level", new Integer(entry.getLevel()));
 
-                    properties.put(EventConstants.MESSAGE, entry.getMessage());
+		    properties.put(EventConstants.MESSAGE,
+				   (entry.getMessage()) != null ? entry.getMessage() : "" );
 
                     properties.put(EventConstants.TIMESTAMP, new Long(
                         entry.getTime()));