added all classes and is working correctly

build.gradle

src/main/java/serializer/CircleSerializer.java

src/main/java/serializer/RectangleSerializer.java

src/main/java/serializer/ShapeReader.java

src/main/java/serializer/ShapeSerializer.java

src/main/java/serializer/ShapeVisitor.java

src/main/java/serializer/ShapeWriter.java

src/main/java/shape/Circle.java

src/main/java/shape/Rectangle.java

src/main/java/shape/Shape.java