Adding Unknown() and Null() methods to the attr.Value interface

Author: Ivan De Marino

attr/value.go

@@ -13,11 +13,16 @@ type Value interface {
 	// Type returns the Type that created the Value.
 	Type(context.Context) Type
 
-	// ToTerraformValue returns the data contained in the Value as
-	// a tftypes.Value.
+	// ToTerraformValue returns the data contained in the Value as a tftypes.Value.
 	ToTerraformValue(context.Context) (tftypes.Value, error)
 
 	// Equal must return true if the Value is considered semantically equal
 	// to the Value passed as an argument.
 	Equal(Value) bool
+
+	// Unknown returns true if the Value is not known.
+	Unknown() bool
+
+	// Null returns true if the Value is null.
+	Null() bool
 }