Add OG_ASSUME_NONNULL_BEGIN/END guards to Subgraph.hpp

Author: jcmosc

Sources/OpenGraphCxx/include/OpenGraphCxx/Graph/Subgraph.hpp

@@ -12,6 +12,8 @@
 #include <OpenGraphCxx/Runtime/metadata.hpp>
 #include <pthread.h>
 
+OG_ASSUME_NONNULL_BEGIN
+
 typedef struct OG_BRIDGED_TYPE(id) OGSubgraphStorage * OGSubgraphRef;
 
 namespace OG {
@@ -28,9 +30,9 @@ class Subgraph final {
 public:
     // MARK: - CF related
 
-    static Subgraph *from_cf(OGSubgraphRef cf_subgraph) OG_NOEXCEPT;
+    static Subgraph *_Nullable from_cf(OGSubgraphRef cf_subgraph) OG_NOEXCEPT;
 
-    OGSubgraphRef to_cf() const OG_NOEXCEPT {
+    _Nullable OGSubgraphRef to_cf() const OG_NOEXCEPT {
         return reinterpret_cast<OGSubgraphRef>(_object);
     }
 
@@ -47,12 +49,12 @@ class Subgraph final {
     }
 
     OG_INLINE OG_CONSTEXPR
-    static Subgraph *get_current() OG_NOEXCEPT {
+    static Subgraph *_Nullable get_current() OG_NOEXCEPT {
         return (OG::Subgraph*)pthread_getspecific(OG::Subgraph::current_key());
     }
 
     OG_INLINE OG_CONSTEXPR
-    static int set_current(Subgraph *subgraph) OG_NOEXCEPT {
+    static int set_current(Subgraph *_Nullable subgraph) OG_NOEXCEPT {
         return pthread_setspecific(OG::Subgraph::current_key(), subgraph);
     }
 
@@ -108,3 +110,5 @@ class SubgraphObject final {
 }
 
 #endif /* Subgraph_hpp */
+
+OG_ASSUME_NONNULL_END