Merge pull request #424 from grails/jamesfredley/fix-GrailsApplicatio…

…nBuilder

switch from Micronaut to Spring ClassUtils

grails-testing-support/src/main/groovy/org/grails/testing/GrailsApplicationBuilder.groovy

@@ -113,7 +113,7 @@ class GrailsApplicationBuilder {
         def configuredEnvironment = context.getEnvironment()
         def beanFactory = context.getBeanFactory()
         def beanExcludes = [ConversionService, Environment, PropertyResolver, ConfigurableEnvironment]
-        def objectMapper = io.micronaut.core.reflect.ClassUtils.forName('com.fasterxml.jackson.databind.ObjectMapper', context.getClassLoader()).orElse(null)
+        def objectMapper = ClassUtils.forName('com.fasterxml.jackson.databind.ObjectMapper', context.getClassLoader())
         if (objectMapper) {
             beanExcludes.add(objectMapper)
         }