refactor: extract interface IA from class A

Author: rodrigo-brito

src/p1/A.java

@@ -1,6 +1,6 @@
 package p1;
 
-public class A {
+public class A implements IA {
   public void m1() {
     System.out.println("m1");
   }

src/p1/IA.java

@@ -0,0 +1,7 @@
+package p1;
+
+public interface IA {
+	void m1();
+
+	void m2();
+}