refactor: extract superclass B from class A

Author: rodrigo-brito

src/p3/A.java

@@ -1,10 +1,6 @@
 package p3;
 
-public class A {
-  public void m1() {
-    System.out.println("m1");
-  }
-
+public class A extends B {
   public void m2() {
     System.out.println("m2");
   }

src/p3/B.java

@@ -0,0 +1,7 @@
+package p3;
+
+public class B {
+  public void m1() {
+    System.out.println("m1");
+  }
+}