I would think that GlassFish is right if you don't have <library-directory> element in your .ear file (see EE.8.2.1Bundled Libraries section of the Java EE 5 spec):
2.A .ear file may contain a directory that contains libraries packaged in JAR files. The library-directory element of the .ear file’s deployment descriptor contains the name of this directory. If a library-directory element isn’t specified, or if the .ear file does not contain a deployment descriptor, the directory named lib is used. An empty library-directory element may be used to specify
that there is no library directory.
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