Set Groovy version to 2.4.15 to work with Gretty.

build.gradle

@@ -11,6 +11,7 @@ buildscript {
 
 apply plugin: 'io.spring.convention.root'
 
+ext['groovy.version'] = "$groovyVersion"
 //ext['spring.version'] = "$springVersion"
 //ext['spring-data-releasetrain.version'] = "$springDataReleaseTrainVersion"
 //ext['spring-session-bom.version'] = "$springSessionBomVersion"

gradle.properties

@@ -1,6 +1,7 @@
 antlrVersion=2.7.7
 apacheGeodeVersion=1.2.1
 apacheTaglibsStandardVersion=1.2.5
+groovyVersion=2.4.15
 javaxServletJspJstlApiVersion=1.2.1
 multithreadedtcVersion=1.01
 pivotalGemFireVersion=9.1.1