@Prince Mishra where did you see:

grails install-plugins spring-security-core

I don't think I've used that since Grails 1.x, so if there is some documentation that still references that for the current versions that needs to get cleaned up. if you point it out to me I can let the Grails team know. If you start using Intellij as your IDE for Grails, it has a Gradle pannel, and on it, there is a refresh icon that does the same as the command:

./gradlew build --refresh-dependencies

IntelliJ is the best IDE I know of at the moment for Grails. You can use the community version, or buy a license for the Ultimate version. I actually pay to have my own license, however, the majority of my employers over the years have paid for a license.