Avoid using the name defaultInitialization differently

Author: stevapple

CodeGeneration/Sources/Utils/SyntaxBuildableChild.swift

@@ -53,7 +53,7 @@ public extension Child {
       return InitializerClauseSyntax(value: NilLiteralExprSyntax())
     }
     guard let token = token, isToken else {
-      return type.defaultInitialization.map { InitializerClauseSyntax(value: $0) }
+      return type.defaultValue.map { InitializerClauseSyntax(value: $0) }
     }
     if token.isKeyword {
       return InitializerClauseSyntax(value: ExprSyntax(".\(raw: token.swiftKind)()"))

CodeGeneration/Sources/Utils/SyntaxBuildableNode.swift

@@ -50,7 +50,7 @@ public extension Node {
 
   /// Assuming this node has a single child without a default value, that child.
   var singleNonDefaultedChild: Child {
-    let nonDefaultedParams = children.filter { $0.type.defaultInitialization == nil }
+    let nonDefaultedParams = children.filter { $0.defaultInitialization == nil }
     precondition(nonDefaultedParams.count == 1)
     return nonDefaultedParams[0]
   }

CodeGeneration/Sources/Utils/SyntaxBuildableType.swift

@@ -50,10 +50,9 @@ public struct SyntaxBuildableType: Hashable {
   }
 
   /// If the type has a default value (because it is optional or a token
-  /// with fixed test), return an expression of the form ` = defaultValue`
-  /// that can be used as the default value for a function parameter.
-  /// Otherwise, return the empty string.
-  public var defaultInitialization: ExprSyntax? {
+  /// with fixed test), return an expression that can be used as the
+  /// default value for a function parameter. Otherwise, return `nil`.
+  public var defaultValue: ExprSyntax? {
     if isOptional {
       return ExprSyntax(NilLiteralExprSyntax())
     } else if let token = token {