Consider the following content in ejb-jar.xml:

<session>
<ejb-name>Bean</ejb-name>
<env-entry>
<env-entry-name>someString</env-entry-name>
<env-entry-value>Hello world</env-entry-value>
<injection-target>
<injection-target-class>org.myapp.ejb.MyEJB</injection-target-class>
<injection-target-name>someString</injection-target-name>
</injection-target>
</env-entry>

Note that we haven't explicitly specified the env-entry-type element. This runs into:

Caused by: java.lang.ClassNotFoundException: Null class name
at org.jboss.classloader.plugins.ClassLoaderUtils.checkClassName(ClassLoaderUtils.java:53) [jboss-classloader.jar:2.2.0.Alpha8]
at org.jboss.classloader.spi.base.BaseClassLoader.loadClass(BaseClassLoader.java:425) [jboss-classloader.jar:2.2.0.Alpha8]
at java.lang.ClassLoader.loadClass(ClassLoader.java:252) [:1.6.0_16]
at org.jboss.injection.EnvEntryEncInjector.getEnvEntryValue(EnvEntryEncInjector.java:66) [:1.5.1]
at org.jboss.injection.EnvEntryEncInjector.inject(EnvEntryEncInjector.java:53) [:1.5.1]
... 82 more

As per the spec, in the absence of explicit env-entry-type, the type has to be inferred from the injection-target (if present).