Allow CI builds without schema download endpoint

Author: EmilJiang

app/build.gradle.kts

@@ -108,9 +108,11 @@ dependencies {
 apollo {
     service("service") {
         packageName.set("com.example.score")
-        introspection {
-            endpointUrl.set(secrets.getProperty("API_URL_DEV"))
-            schemaFile.set(file("src/main/graphql/schema.graphqls"))
+        secrets.getProperty("API_URL_DEV")?.takeIf { it.isNotBlank() }?.let { apiUrl ->
+            introspection {
+                endpointUrl.set(apiUrl)
+                schemaFile.set(file("src/main/graphql/schema.graphqls"))
+            }
         }
     }
 }