When turning on DEBUG logging, toString() causes the following exception.
It happens in an OSGi environment.

SLF4J: Failed toString() invocation on an object of type [org.apache.tomcat.jdbc.pool.DataSource]
2013-03-12 14:17:13,612 | DEBUG | Blueprint Extender: 1    | ServiceRecipe                    | lueprint.container.ServiceRecipe  276 | 7 - org.apache.aries.blueprint.core - 1.1.0 | Creating service instance
java.lang.NoClassDefFoundError: javax/naming/spi/ObjectFactory
    at java.lang.ClassLoader.defineClass1(Native Method)
    at java.lang.ClassLoader.defineClass(ClassLoader.java:791)
    at org.apache.felix.framework.BundleWiringImpl$BundleClassLoader.findClass(BundleWiringImpl.java:2128)
    at org.apache.felix.framework.BundleWiringImpl.findClassOrResourceByDelegation(BundleWiringImpl.java:1432)
    at org.apache.felix.framework.BundleWiringImpl.access$400(BundleWiringImpl.java:72)
    at org.apache.felix.framework.BundleWiringImpl$BundleClassLoader.loadClass(BundleWiringImpl.java:1843)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:356)
    at org.apache.tomcat.jdbc.pool.PoolProperties.toString(PoolProperties.java:804)
    at java.lang.String.valueOf(String.java:2854)
    at java.lang.StringBuilder.append(StringBuilder.java:128)
    at org.apache.tomcat.jdbc.pool.DataSourceProxy.toString(DataSourceProxy.java:215)
    at org.slf4j.helpers.MessageFormatter.safeObjectAppend(MessageFormatter.java:304)
    at org.slf4j.helpers.MessageFormatter.deeplyAppendParameter(MessageFormatter.java:276)
    at org.slf4j.helpers.MessageFormatter.arrayFormat(MessageFormatter.java:230)
    at org.slf4j.helpers.MessageFormatter.format(MessageFormatter.java:124)
    at org.ops4j.pax.logging.slf4j.Slf4jLogger.debug(Slf4jLogger.java:280)
    at org.apache.aries.blueprint.container.ServiceRecipe.createService(ServiceRecipe.java:302)
    at org.apache.aries.blueprint.container.ServiceRecipe.internalGetService(ServiceRecipe.java:249)
    at org.apache.aries.blueprint.container.ServiceRecipe.internalCreate(ServiceRecipe.java:146)
    at org.apache.aries.blueprint.di.AbstractRecipe$1.call(AbstractRecipe.java:79)
    at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:334)
    at java.util.concurrent.FutureTask.run(FutureTask.java:166)
    at org.apache.aries.blueprint.di.AbstractRecipe.create(AbstractRecipe.java:88)
    at org.apache.aries.blueprint.container.BlueprintRepository.createInstances(BlueprintRepository.java:245)
    at org.apache.aries.blueprint.container.BlueprintRepository.createAll(BlueprintRepository.java:183)
    at org.apache.aries.blueprint.container.BlueprintContainerImpl.instantiateEagerComponents(BlueprintContainerImpl.java:668)
    at org.apache.aries.blueprint.container.BlueprintContainerImpl.doRun(BlueprintContainerImpl.java:370)
    at org.apache.aries.blueprint.container.BlueprintContainerImpl.run(BlueprintContainerImpl.java:261)
    at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471)
    at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:334)
    at java.util.concurrent.FutureTask.run(FutureTask.java:166)
    at org.apache.aries.blueprint.container.ExecutorServiceWrapper.run(ExecutorServiceWrapper.java:106)
    at org.apache.aries.blueprint.utils.threading.impl.DiscardableRunnable.run(DiscardableRunnable.java:48)
    at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471)
    at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:334)
    at java.util.concurrent.FutureTask.run(FutureTask.java:166)
    at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$201(ScheduledThreadPoolExecutor.java:178)
    at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:292)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
    at java.lang.Thread.run(Thread.java:722)
Caused by: java.lang.ClassNotFoundException: javax.naming.spi.ObjectFactory not found by org.apache.tomcat.jdbc [165]
    at org.apache.felix.framework.BundleWiringImpl.findClassOrResourceByDelegation(BundleWiringImpl.java:1460)
    at org.apache.felix.framework.BundleWiringImpl.access$400(BundleWiringImpl.java:72)
    at org.apache.felix.framework.BundleWiringImpl$BundleClassLoader.loadClass(BundleWiringImpl.java:1843)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:356)
    ... 41 more