label is optional

Author: robrichard

spec/Section 3 -- Type System.md

@@ -1932,7 +1932,7 @@ type ExampleType {
 
 ### @defer
 ```graphql
-directive @defer(label: String!, if: Boolean) on FRAGMENT_SPREAD | INLINE_FRAGMENT
+directive @defer(label: String, if: Boolean) on FRAGMENT_SPREAD | INLINE_FRAGMENT
 ```
 The `@defer` directive may be provided for fragment spreads and inline fragments to 
 inform the executor to delay the execution of the current fragment to indicate 
@@ -1958,7 +1958,7 @@ fragment someFragment on User {
 
 ### @stream
 ```graphql
-directive @stream(label: String!, initialCount: Int!, if: Boolean) on FIELD
+directive @stream(label: String, initialCount: Int!, if: Boolean) on FIELD
 ```
 The `@stream` directive may be provided for a field of `List` type so that the 
 backend can leverage technology such as asynchronous iterators to provide a partial

spec/Section 7 -- Response.md

@@ -258,7 +258,8 @@ If the response of the GraphQL operation is an event stream, subsequent values
 may contain a string field `label`. This `label` is the same label passed to 
 the `@defer` or `@stream` directive that triggered this value. This allows 
 clients to identify which `@defer` or `@stream` directive is associated with
-this value.
+this value. `label` will not be present if the corresponding `@defer` or 
+`@stream` directive is not passed a `label` argument.
 
 ## Serialization Format