Dev Test for : https://glassfish.dev.java.net/issues/show_bug.cgi?id=667
[doesn't uphold the close() contract of java.sql.Connection]

Closing a connection multiple times should not throw any exception.

Further, duplicate close requests on a connection must be no-op.
[refer  JDBC specification,  java.sql.Connection javadoc]
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public void close() throws SQLException
    Calling the method close on a Connection object that is already closed is a no-op.
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This dev tests tests whether multiple close on same connection work fine.