How to read our .h5 format and provide all required data to snap

I’m implementing our own product reader plugin for snap
we have our .h5 structure.
which File type you recommend to use I tried to use NetcdfFile but we store our data directly inside rootGroup.variables not inside rootGroup.attributes
Any guide or help?
Should I create our own File types?
and in that case which interface I should implement?
or there is way to map rootGroup.attributes to rootGroup.variables [Is there way to create Attribute from Variable] ?