The imagemosaic-work branch is a branch containing some refactoring/improvements of the imagemosaic plugin on trunk.
Basically:
- we are porting the footprint support from 2.6.x branch which requires to take care of the actual granuleCatalog entities.
- We are improving ImageMosaic setup on top of an in memory MosaicDescriptor instead of a file based index catalog. 
- We are doing some improvements such as allowing to specify Interpolation to be used in mosaicking and exposing the mosaic footprint as a ROI property in the output rendered image.
- We are doing some work on refactoring in order to move the underlying decision logics on the Catalog entities.
- We would also like to allow the granule catalog to return granules as well as a set of information to be used to access that granule (ImageReadParam, imageIndex, ...) depending on the specific request (involved OverviewLevel, overview/decimation policies, ...)