fix: graphql context plus map non null values (#2026)

### 📝 Description
#2024

Co-authored-by: Samuel Vazquez <[email protected]>

Author: samuelAndalon

generator/graphql-kotlin-schema-generator/src/main/kotlin/com/expediagroup/graphql/generator/extensions/GraphQLContextExtensions.kt

@@ -62,7 +62,7 @@ operator fun GraphQLContext.plus(graphQLContext: GraphQLContext): GraphQLContext
  * @param map which values will be added into [this] GraphQLContext
  * @return current GraphQLContext with values of [map] added
  */
-operator fun GraphQLContext.plus(map: Map<*, Any?>): GraphQLContext =
+operator fun GraphQLContext.plus(map: Map<*, Any>): GraphQLContext =
     putAll(map)
 
 /**