• I'm writing an aggregated report for the clover plugin. It needs to locate all children's clover databases and merge them into a single one and then generate a report out of it
• The location of the Clover databases is stored in plugin's configuration
• The problem is that I cannot access a plugin configuration using the plugin API

This is a general problem. By definition any aggregation mojo needs to access configuration information from its children. Some time out of sheer luck the information the plugin needs is found in the general section of the POM. However this is very limited and forbids any use case where the configuration is stored in <plugin><configuration>.