PR feedback: Use core field format

Author: FranAguilera

platform/jvm/capture/src/main/kotlin/io/bitdrift/capture/attributes/ClientAttributes.kt

@@ -83,7 +83,7 @@ internal class ClientAttributes(
             // Device model name.
             "model" to model,
             // Device manufacturer name.
-            "manufacturer" to manufacturer,
+            "_manufacturer" to manufacturer,
             // The SDK level (e.g. 35).
             "_os_api_level" to osApiLevel.toString(),
             // The version of this package, as specified by the manifest's `versionName` attribute.

platform/jvm/capture/src/test/kotlin/io/bitdrift/capture/attributes/ClientAttributesTest.kt

@@ -260,7 +260,7 @@ class ClientAttributesTest {
 
         val fields = clientAttributes.invoke()
 
-        assertThat(fields).containsEntry("manufacturer", "unknown")
+        assertThat(fields).containsEntry("_manufacturer", "unknown")
     }
 
     @Test