chore(spring-boot): refactor provided scalars

Author: WipeAir

graphql-kotlin-toolkit-spring-boot/src/main/kotlin/com/auritylab/graphql/kotlin/toolkit/spring/internal/InternalWiringFactory.kt

@@ -1,7 +1,7 @@
 package com.auritylab.graphql.kotlin.toolkit.spring.internal
 
 import com.auritylab.graphql.kotlin.toolkit.spring.annotation.AnnotationResolver
-import com.auritylab.graphql.kotlin.toolkit.spring.provided.providedUploadScalar
+import com.auritylab.graphql.kotlin.toolkit.spring.provided.ProvidedScalars
 import graphql.schema.DataFetcher
 import graphql.schema.GraphQLScalarType
 import graphql.schema.TypeResolver
@@ -19,7 +19,7 @@ import org.springframework.context.annotation.Configuration
 class InternalWiringFactory(
     private val annotationResolver: AnnotationResolver
 ) : WiringFactory {
-    private val providedScalars = mapOf(Pair("Upload", providedUploadScalar))
+    private val providedScalars = mapOf(Pair("Upload", ProvidedScalars.upload))
 
     override fun getDataFetcher(environment: FieldWiringEnvironment): DataFetcher<*> =
         annotationResolver.getResolver(environment)!!

graphql-kotlin-toolkit-spring-boot/src/main/kotlin/com/auritylab/graphql/kotlin/toolkit/spring/provided/ProvidedScalars.kt

@@ -0,0 +1,18 @@
+package com.auritylab.graphql.kotlin.toolkit.spring.provided
+
+import graphql.schema.Coercing
+import graphql.schema.GraphQLScalarType
+
+object ProvidedScalars {
+    /**
+     * The "Upload" scalar with the according [Coercing] implementation. The coercing will always convert into an
+     * empty string, as the uploaded file will not be transferred through the variables.
+     */
+    val upload = GraphQLScalarType.newScalar()
+        .name("Upload")
+        .coercing(object : Coercing<String, String> {
+            override fun parseValue(input: Any?): String = ""
+            override fun parseLiteral(input: Any?): String = ""
+            override fun serialize(dataFetcherResult: Any?): String = ""
+        }).build()
+}