Add additional feature flag checks

Author: ethan-kusters

Sources/SwiftDocC/Converter/TopicRenderReferenceEncoder.swift

@@ -155,7 +155,7 @@ enum TopicRenderReferenceEncoder {
         // Append closing "}"
         renderNodeData.append(fragments.closingBrace)
 
-        if encodeAccumulatedVariantOverrides {
+        if encodeAccumulatedVariantOverrides, !variantOverrides.isEmpty {
             // Insert the "variantOverrides" key
             renderNodeData.append(fragments.variantOverridesKey)
             let variantOverrideData = try encoder.encode(VariantOverrides(values: variantOverrides))

Sources/SwiftDocC/Infrastructure/Symbol Graph/SymbolReference.swift

@@ -172,6 +172,10 @@ private extension Array where Element == String {
 
 extension UnifiedSymbolGraph.Symbol {
     var sourceLanguages: Set<SourceLanguage> {
+        guard FeatureFlags.current.isExperimentalObjectiveCSupportEnabled else {
+            return [.swift]
+        }
+        
         // FIXME: Replace with new SymbolKit API once available.
         // Adding a dedicated SymbolKit API for this purpose is tracked
         // with SR-15551 and rdar://85982095.

Sources/SwiftDocC/Semantics/Symbol/Symbol.swift

@@ -420,11 +420,19 @@ extension UnifiedSymbolGraph.Symbol {
 
     /// Returns the primary symbol to use as documentation source.
     var documentedSymbol: SymbolGraph.Symbol? {
+        guard FeatureFlags.current.isExperimentalObjectiveCSupportEnabled else {
+            return defaultSymbol
+        }
+        
         return symbol(forSelector: documentedSymbolSelector)
     }
 
     /// Returns the primary symbol selector to use as documentation source.
     var documentedSymbolSelector: UnifiedSymbolGraph.Selector? {
+        guard FeatureFlags.current.isExperimentalObjectiveCSupportEnabled else {
+            return defaultSelector
+        }
+        
         // We'll prioritize the first documented 'swift' symbol, if we have
         // one.
         return docComment.keys.first { selector  in