feat(solana): add nullable tag

common/defs/solana/programs.json

@@ -1573,7 +1573,8 @@
             {
               "name": "new_authority",
               "type": "authority",
-              "optional": true
+              "optional": false,
+              "nullable": true
             }
           ],
           "references": [

common/tests/fixtures/solana/sign_tx.token_program.json

@@ -281,6 +281,48 @@
         "expected_signature": "7a96fb6cc283a10e26c9d330e8f2b2892d23698e008c959c29eb124a9c835fc0125865af4ee2ee267fe5ed03e51029f4244b05a592fd5c7969f5a9890ceef902"
       }
     },
+    {
+      "description": "Set Authority - null authority",
+      "parameters": {
+        "address": "m/44'/501'/0'/0'",
+        "construct": {
+          "version": null,
+          "header": {
+            "signers": 1,
+            "readonly_signers": 0,
+            "readonly_non_signers": 1
+          },
+          "accounts": [
+            "14CCvQzQzHCVgZM3j9soPnXuJXh1RmCfwLVUcdfbZVBS",
+            "FUqrjRRtF1LiptdFqaFxipE8R3YfCE4k56xwm5n1piqX",
+            "TokenkegQfeZyiNwAJbNbGKPFXCWuBvf9Ss623VQ5DA"
+          ],
+          "blockhash": "2p4rYZAaFfV5Uk5ugdG5KPNty9Uda9B3b4gWB8qnNqak",
+          "instructions": [
+            {
+              "program_index": 2,
+              "accounts": {
+                "mint_account": 1,
+                "current_authority": 0,
+                "multisig_signers": []
+              },
+              "data": {
+                "instruction_id": 6,
+                "authority_type": 1,
+                "new_authority": {
+                  "is_included": false,
+                  "value": null
+                }
+              }
+            }
+          ],
+          "luts": []
+        }
+      },
+      "result": {
+        "expected_signature": "f983c4f3ac794bf02e67d3320c91e515c3de649b377c61c25546699fe6f551ffc8c022853823eb81cf785e71a5bbb78f5cbcfd49eb38480629bdc906c5c50202"
+      }
+    },
     {
       "description": "Set Authority - Multisig",
       "parameters": {

core/src/apps/solana/layout.py

@@ -80,15 +80,24 @@ async def confirm_instruction(
                 continue
 
             if ui_property.default_value_to_hide == value:
-                continue
+                # currently we can define a default value to hide,
+                # but it needs to be of the type that the property is of (such as public key for new_authority)
+                # and for nullable values(such as new_authority) we want to display it to the user
+                if not property_template.is_nullable or value is not None:
+                    continue
 
+            display_text = (
+                "Not set"
+                if value is None
+                else property_template.format(instruction, value)
+            )
             await confirm_properties(
                 "confirm_instruction",
                 f"{instruction_index}/{instructions_count}: {instruction.ui_name}",
                 (
                     (
                         ui_property.display_name,
-                        property_template.format(instruction, value),
+                        display_text,
                     ),
                 ),
             )

core/src/apps/solana/transaction/instruction.py

@@ -50,9 +50,24 @@ def parse_instruction_data(
         parsed_data = {}
         for property_template in property_templates:
             is_included = True
+            # Property cannot be both optional and nullable as if there are multiple such properties in 1 instruction
+            # it could lead to non-deterministic parsing
+            # it is validated by mako template as well
+            if property_template.is_nullable and property_template.is_optional:
+                raise DataError("Parameter is nullable and optional")
+
             if property_template.is_optional:
                 is_included = True if reader.get() == 1 else False
 
+            if property_template.is_nullable:
+                is_included = True if reader.get() == 1 else False
+                if not is_included:
+                    # A default (null) value is included in the parsed message for nullable properties
+                    # (e.g. new_authority in Set Authority instruction) even if the is_included flag is not set.
+                    # We can safely discard this value.
+                    if reader.remaining_count() != 0:
+                        property_template.parse(reader)
+
             parsed_data[property_template.name] = (
                 property_template.parse(reader) if is_included else None
             )