[BAEL-3348] Moved code to algorithm-4

mapstruct/src/main/java/com/baeldung/mapper/PoundToKilogramMapper.java

@@ -0,0 +1,13 @@
+package com.baeldung.mapper;
+
+import org.mapstruct.Qualifier;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+@Qualifier
+@Target(ElementType.METHOD)
+@Retention(RetentionPolicy.CLASS)
+public @interface PoundToKilogramMapper {}