try class

src/org/SHS/Platforms.groovy

@@ -0,0 +1,13 @@
+package org.SHS
+
+class Platforms {
+	def steps
+	Platforms(steps) {
+		this.steps = steps
+		// stage("Download platforms.json") {
+			steps.sh "rm -rf platforms"
+			steps.sh "git clone --depth 1 ${env.PLATFORMS_GIT} platforms"
+		//}
+		
+	}
+}

src/org/SHS/platforms.groovy

@@ -1,5 +0,0 @@
-package org.SHS
-
-def sayHello(name) {
-    println "Hello, ${name}!"
-}