JBIDE-18420 - NPE protection
WFLY-3189 and JBIDE-18319

Add missing catalog entries.

Add catalog entry for namespace "http://www.jboss.com/xml/ns/javaee" so
that others can refer to it without specifying schema location.

Add catalog entry for namespace "urn:clustering:1.0" which is mentioned
for example in
https://docs.jboss.org/author/display/AS71/jboss-ejb3.xml+Reference but
missing in this plugin and in the JBoss EAP 6 distribution as far as I
see.

Do not use schema location for http://java.sun.com/xml/ns/javaee".

XML validators seem to get confused when schema location is specified
and imports / includes are circular. Instead rely on entries in XML
catalogue.

Do not use schema location in schema element, as far as I unterstand it
is of no use there.

Do not use schema location for "http://www.jboss.com/xml/ns/javaee".

XML validators seem to get confused when schema location is specified
and imports / includes are circular. Instead rely on entries in XML
catalogue.

Remove element "assembly-descriptor" from complex type
"jboss-ejb-jarType" since it is already defined in the parent type and
adding it again is not allowed.

Add XML schema for namespace "urn:clustering:1.0" which is mentioned in
https://docs.jboss.org/author/display/AS71/jboss-ejb3.xml+Reference, but
missing this plugin and in JBoss EAP 6 distribution. Based on
"jboss-ejb-security_1.0.xsd".

Remove schema location in schema element, as far as I understand it is
of no use here.

Do not use schema location for "http://java.sun.com/xml/ns/javaee",
validators seem to get confused by it, depend on catalogue entries
instead.

Remove schema location in schema element, as far as I understand it is
of no use here.

Do not use schema location for "http://java.sun.com/xml/ns/javaee",
validators seem to get confused by it, depend on catalogue entries
instead.

Test, update two files

Remove the rogue clustering xsd