android: fix warning

android/build.gradle

+import groovy.json.JsonSlurper
+
 // Top-level build file where you can add configuration options common to all
 // sub-projects/modules.
 
                 if (details.requested.group == 'com.facebook.react'
                         && details.requested.name == 'react-native') {
                     def file = new File("$rootDir/../node_modules/react-native/package.json")
-                    def version = new groovy.json.JsonSlurper().parseText(file.text).version
+                    def version = new JsonSlurper().parseText(file.text).version
                     details.useVersion version
                 }
                 if (details.requested.group == 'org.webkit'
                         && details.requested.name == 'android-jsc') {
                     def file = new File("$rootDir/../node_modules/jsc-android/package.json")
-                    def version = new groovy.json.JsonSlurper().parseText(file.text).version
+                    def version = new JsonSlurper().parseText(file.text).version
                     details.useVersion "r${version.tokenize('.')[0]}"
                 }
             }
     afterEvaluate { project ->
         if (project.name.startsWith('react-native-')) {
             def npmManifest = project.file('../package.json')
-            def json = new groovy.json.JsonSlurper().parseText(npmManifest.text)
+            def json = new JsonSlurper().parseText(npmManifest.text)
 
             // React Native modules have an npm peer dependency on react-native,
             // they do not have an npm dependency on it. Further below though we