Replace constant strings with constant vals

src/main/kotlin/DocumentsSearchDocBuilder.kt

@@ -37,6 +37,7 @@ import org.memobase.helpers.Filter
 import org.memobase.helpers.InstitutionAndRecordSetExtractionHelper.extractInstitution
 import org.memobase.helpers.InstitutionAndRecordSetExtractionHelper.extractRecordSet
 import org.memobase.helpers.Constants
+import org.memobase.helpers.JsonUtility
 import org.memobase.helpers.TranslationMappers
 import org.memobase.model.DocumentsSearchDoc
 import org.memobase.model.EnrichedDigitalMetadata
@@ -53,7 +54,7 @@ class DocumentsSearchDocBuilder(
 
     fun transform(key: String, input: Map<String, JsonObject>): Schema {
 
-        val record = input["record"] ?: throw InvalidInputException("No record defined in the message.")
+        val record = input[JsonUtility.recordTag] ?: throw InvalidInputException("No record defined in the message.")
         val digitalObject =
             input.values.firstOrNull { it["@type"] == NS.rico + "Instantiation" && it["type"] == "digitalObject" }
         val physicalObject =

src/main/kotlin/InstitutionSearchDocBuilder.kt

@@ -27,6 +27,7 @@ import org.memobase.helpers.Date
 import org.memobase.helpers.ElasticSearchWrapper
 import org.memobase.helpers.Extract
 import org.memobase.helpers.Constants
+import org.memobase.helpers.JsonUtility
 import org.memobase.helpers.TranslationMappers
 import org.memobase.model.FacetContainer
 import org.memobase.model.InstitutionSearchDoc
@@ -42,7 +43,7 @@ class InstitutionSearchDocBuilder(
 
     fun transform(key: String, input: Map<String, JsonObject>): Schema {
         val institution =
-            input["institution"] ?: throw InvalidInputException("No institution entity found in message $key.")
+            input[JsonUtility.institutionTag] ?: throw InvalidInputException("No institution entity found in message $key.")
         val identifiers = mutableListOf<JsonObject>()
         val cantons = mutableListOf<FacetContainer>()
         val municipalities = mutableListOf<LanguageContainer>()