replace DesktopType by extendable class

src/main/kotlin/org/domaindrivenarchitecture/provs/desktop/domain/DesktopType.kt

@@ -1,5 +1,37 @@
 package org.domaindrivenarchitecture.provs.desktop.domain
 
-enum class DesktopType {
-    BASIC, OFFICE, IDE
-}
+
+/**
+ * Provides desktop types. For each type a different set of software and packages is installed, see README.md.
+ */
+open class DesktopType(val name: String) {
+
+    // A regular class is used rather than enum class in order to allow extending DesktopType by subclassing.
+
+    companion object {
+
+        val BASIC = DesktopType("BASIC")
+        val OFFICE = DesktopType("OFFICE")
+        val IDE = DesktopType("IDE")
+
+        @JvmStatic
+        protected val values = listOf(BASIC, OFFICE, IDE)
+
+        fun valueOf(value: String): DesktopType {
+            return valueOf(value, values)
+        }
+        fun valueOf(value: String, v: List<DesktopType>): DesktopType {
+            for (t in v) {
+                if (value.uppercase().equals(t.name)) {
+                    return t
+                }
+            }
+            throw RuntimeException("No DesktopType found for value: $value")
+        }
+    }
+
+    override fun toString(): String {
+        return name
+    }
+}
+