IntelliJ content module providing language injection for Grails code — injecting HQL, SQL and other languages into the string literals and GSP positions where Grails expects them.
Configuration is data rather than code: the module ships META-INF/languageInjections.xml and points at it from its descriptor with <injectionConfig config="META-INF/languageInjections.xml"/>.
Content module org.apache.grails.intellij.module.langInjection, shipped as lib/modules/org.apache.grails.intellij.module.langInjection.jar.
This is the only module whose descriptor depends on a bundled module rather than a plugin (<module name="intellij.platform.langInjection"/>), and the only one with no Java/Kotlin sources at all — it is resources only.