Add Swagger Documentation for Payload

This is a 1:1 copy from ApiItemPayload

src/main/kotlin/no/nb/mlt/wls/infrastructure/callbacks/NotificationItemPayload.kt

@@ -1,21 +1,73 @@
 package no.nb.mlt.wls.infrastructure.callbacks
 
+import io.swagger.v3.oas.annotations.media.Schema
+import io.swagger.v3.oas.annotations.media.Schema.AccessMode.READ_ONLY
 import no.nb.mlt.wls.domain.model.Environment
 import no.nb.mlt.wls.domain.model.HostName
 import no.nb.mlt.wls.domain.model.Item
 import no.nb.mlt.wls.domain.model.Owner
 import no.nb.mlt.wls.domain.model.Packaging
 
 data class NotificationItemPayload(
+    @Schema(
+        description = "ID from the host system which owns the item.",
+        examples = ["item-12345"]
+    )
     val hostId: String,
+    @Schema(
+        description = "Name of the host system which manages the item.",
+        examples = ["AXIELL", "ALMA", "ASTA", "BIBLIOFIL"]
+    )
     val hostName: HostName,
+    @Schema(
+        description =
+            "Description of the item for easy identification in the warehouse system. " +
+                "Usually an item title/name, e.g. book title, film name, etc. or contents description.",
+        examples = ["Tyven, tyven skal du hete", "Avisa Hemnes", "Kill Buljo"]
+    )
     val description: String,
+    @Schema(
+        description = "What kind of item category the item belongs to, e.g. Books, Issues, Films, etc.",
+        examples = ["BOOK", "ISSUE", "Arkivmateriale", "Film_Frys"]
+    )
     val itemCategory: String,
+    @Schema(
+        description = "What kind of environment the item should be stored in, e.g. NONE, FRYS, MUGG_CELLE, etc.",
+        examples = ["NONE", "FRYS"]
+    )
     val preferredEnvironment: Environment,
+    @Schema(
+        description =
+            "Whether the item is a single object or a box/abox/crate of other items. " +
+                "NONE is for single objects, BOX is for boxes, ABOX is for archival boxes, and CRATE is for crates.",
+        examples = ["NONE", "BOX", "ABOX", "CRATE"]
+    )
     val packaging: Packaging,
+    @Schema(
+        description = "Who's the owner of the item.",
+        examples = ["NB", "ARKIVVERKET"]
+    )
     val owner: Owner,
+    @Schema(
+        description = "Callback URL for the item used to update the item in the host system.",
+        example = "https://example.com/send/callback/here"
+    )
     val callbackUrl: String?,
+    @Schema(
+        description = "Where the item is located, e.g. SYNQ_WAREHOUSE, AUTOSTORE, KARDEX, etc.",
+        examples = ["SYNQ_WAREHOUSE", "AUTOSTORE", "KARDEX"],
+        accessMode = READ_ONLY,
+        required = false
+    )
     val location: String?,
+    @Schema(
+        description =
+            "Quantity on hand of the item, this denotes if the item is in storage or not. " +
+                "If the item is in storage then quantity is 1.0, if it's not in storage then quantity is 0.0.",
+        examples = [ "0.0", "1.0"],
+        accessMode = READ_ONLY,
+        required = false
+    )
     val quantity: Double?
 )