PostGrid coverage reference persistance

When you manipulate a GridCoverageTable for to long
and make redondant changes to Elevation and Time ranges.
At on moment he doesnt found the coverageReference.

The solution is to use table.flush() if it doesnt found the reference and retry.

temporary solution :
CoverageReference ref = table.getEntry();
if(ref == null){
//TODO sometimes the postgrid reader go a bit crazy and found no coveragreference
//if so clear the cache and retry
table.flush();
ref = table.getEntry();
}
coverage = ref.getCoverage(null);