Add custom test infrastructure.

src/main/java/ysoserial/PayloadTest.java

@@ -0,0 +1,24 @@
+/**
+ * © 2016 AgNO3 Gmbh & Co. KG
+ * All right reserved.
+ * 
+ * Created: 05.03.2016 by mbechler
+ */
+package ysoserial;
+
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+
+/**
+ * @author mbechler
+ *
+ */
+@Retention(RetentionPolicy.RUNTIME)
+public @interface PayloadTest {
+
+    String skip() default "";
+    
+    String precondition() default "";
+    
+    String harness() default "";
+}

src/main/java/ysoserial/payloads/Jdk7u21.java

@@ -6,6 +6,7 @@ import java.util.LinkedHashSet;
 
 import javax.xml.transform.Templates;
 
+import ysoserial.PayloadTest;
 import ysoserial.payloads.annotation.Dependencies;
 import ysoserial.payloads.util.Gadgets;
 import ysoserial.payloads.util.PayloadRunner;
@@ -52,6 +53,7 @@ LinkedHashSet.readObject()
 
 @SuppressWarnings({ "rawtypes", "unchecked" })
 @Dependencies()
+@PayloadTest ( precondition = "isApplicableJavaVersion")
 public class Jdk7u21 implements ObjectPayload<Object> {
 
 	public Object getObject(final String command) throws Exception {
@@ -77,6 +79,21 @@ public class Jdk7u21 implements ObjectPayload<Object> {
 
 		return set;
 	}
+	
+	public static boolean isApplicableJavaVersion() {
+	    String property = System.getProperties().getProperty("java.version");
+	    if ( property == null ) {
+	        return false;
+	    }
+	    String parts[] = property.split("\\.|_|-");;
+	    int major   = Integer.parseInt(parts[1]);
+	    int minor   = Integer.parseInt(parts[2]);
+	    int update  = Integer.parseInt(parts[3]);
+	    if ( major < 7 || (major == 7 && update <= 21) ) {
+	        return true;
+	    }
+	    return false;
+	}
 
 	public static void main(final String[] args) throws Exception {
 		PayloadRunner.run(Jdk7u21.class, args);