7.0 has a lot of new functionality and a few changes to the Kibana Plugin APIs.
Kibana management index pattern URL changes
Kibana management URLs pertaining to index patterns have been changed to accurately reflect their content, from management/kibana/index or management/kibana/indices to managemen/kibana/index_pattern or management/kibana/index_patterns.
Impact: References to these URLs will need to be updated.
via #30779
Removed legacy response handler
In this release we removed the already deprecated legacy response handler for visualizations. See Kibana Plugin API changes in 6.5 for more information.
via #28985
Removed legacyIcon from visualizations
The already deprecated legacyIcon was removed and you have to use image or icon on a visualization to specify it's icon. See also Kibana Plugin API changes in 6.5
via #28981