Refrain from logging if verifying log factory plugin.

git-svn-id: https://svn.apache.org/repos/asf/openjpa/branches/1.0.x@1481688 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/openjpa-lib/src/main/java/org/apache/openjpa/lib/conf/ConfigurationImpl.java b/openjpa-lib/src/main/java/org/apache/openjpa/lib/conf/ConfigurationImpl.java
index bbf651e..3fb79fa 100644
--- a/openjpa-lib/src/main/java/org/apache/openjpa/lib/conf/ConfigurationImpl.java
+++ b/openjpa-lib/src/main/java/org/apache/openjpa/lib/conf/ConfigurationImpl.java
@@ -217,7 +217,6 @@
     }
 
     public void setLog(String log) {
-        assertNotReadOnly();
         logFactoryPlugin.setString(log);
     }
 
diff --git a/openjpa-lib/src/main/java/org/apache/openjpa/lib/conf/PluginValue.java b/openjpa-lib/src/main/java/org/apache/openjpa/lib/conf/PluginValue.java
index 362072a..e15740f 100644
--- a/openjpa-lib/src/main/java/org/apache/openjpa/lib/conf/PluginValue.java
+++ b/openjpa-lib/src/main/java/org/apache/openjpa/lib/conf/PluginValue.java
@@ -20,6 +20,7 @@
 
 import org.apache.commons.lang.StringUtils;
 import org.apache.openjpa.lib.log.Log;
+import org.apache.openjpa.lib.log.LogFactory;
 import org.apache.openjpa.lib.util.Localizer;
 import org.apache.openjpa.lib.util.ParseException;
 
@@ -104,7 +105,8 @@
         
         // ensure plugin value is compatible with plugin type
         if (obj != null && !type.isAssignableFrom(obj.getClass())) {
-            Log log = (conf == null) ? null : conf.getConfigurationLog();
+            Log log = (conf == null || type.equals(LogFactory.class)) 
+                      ? null : conf.getConfigurationLog();
             String msg = getIncompatiblePluginMessage(obj, type);
             if (log != null && log.isErrorEnabled()) {
             	log.error(msg);