I have my persistence.xml with the same name using TopLink under the META-INF directory. Then, I have my code calling it with:
persistence.xml
TopLink
META-INF
Mine got resolved by adding info in persistence.xml e.g. org.eclipse.persistence.jpa.PersistenceProvider and then making sure you have the library on classpath e.g. in Maven add dependency like
org.eclipse.persistence.jpa.PersistenceProvider
org.eclipse.persistence eclipselink 2.5.0