Upgrade openapi plugin version from 7.7 to 7.11.

In version 7.7 generating documentation via the openApi gradle task results in the following misleading warning:

"More than one inline schema specified in allOf:. Only the first one is recognized. All others are ignored."

See comments on this PR: OpenAPITools/openapi-generator#19646.

In later versions of the plugin - and rather than fixing the issue - the severity of the warning has been reduced from WARN to DEBUG.  See: https://github.com/OpenAPITools/openapi-generator/pull/19646/files.

Also set removeEnumValuePrefix = true since this is a new additional property added to more recent versions which removes the prefix for enum definitions.  Previously in version 7.7 prefixes were removed automatically and the property didn't exist.  Since it defaults to false we need to set it to true.  See OpenAPITools/openapi-generator#20452.

Unfortunately this property isn't documented in the README https://github.com/OpenAPITools/openapi-generator/blob/master/docs/generators/kotlin-server.md#config-options.

build.gradle.kts

@@ -3,7 +3,7 @@ import org.apache.commons.io.FileUtils
 plugins {
   id("uk.gov.justice.hmpps.gradle-spring-boot") version "6.1.0"
   kotlin("plugin.spring") version "2.0.20"
-  id("org.openapi.generator") version "7.7.0"
+  id("org.openapi.generator") version "7.11.0"
   id("org.jetbrains.kotlin.plugin.jpa") version "1.9.22"
   id("io.gatling.gradle") version "3.13.1"
   id("io.gitlab.arturbosch.detekt") version "1.23.7"
@@ -239,6 +239,7 @@ openApiGenerate {
   typeMappings.put("DateTime", "Instant")
   importMappings.put("Instant", "java.time.Instant")
   templateDir.set("$rootDir/openapi")
+  additionalProperties.put("removeEnumValuePrefix", "true")
 }
 
 registerAdditionalOpenApiGenerateTask(