The idea.sh script invokes make, but doesn't specify a configuration. So, when multiple configurations are present, this results in an error like this:

$ bash bin/idea.sh java.base
Error: No CONF given, but more than one configuration found.
Available configurations in /mnt/c/jdk/build:
* conf1
* conf2
* conf3
Please retry building with CONF=<config pattern> (or SPEC=<spec file>).

/mnt/c/jdk/make/Init.gmk:124: *** Cannot continue. Stop.

Suggestion to add an option to the script for specifying the configuration.