dap4/d4cdm/src/main/java/dap4/cdm/nc2/DapNetcdfFile.java
@Override
    public synchronized void close()
            throws java.io.IOException
    {
        if(closed) return;
        closed = true; // avoid circular calls
        dsp = null;
        // nodemap = null;  unused?
    }
@Override
    public synchronized void close()
            throws java.io.IOException
    {
        if(closed) return;
        closed = true; // avoid circular calls
        dsp = null;
        // nodemap = null;  unused?
    }
Close all resources (files, sockets, etc) associated with this file.

@throws java.io.IOException if error when closing