Make nested SapHeating.has_fixed_air_conditioning optional across all RdSAP schemas

Some lodged certs omit the sap_heating.has_fixed_air_conditioning key,
which the generic from_dict loader treats as a required field and
rejects outright. Two prior commits (26651ca71, 8074f4152) fixed the
duplicate top-level field of the same name but left this nested copy
untouched; a third pass (44991bed0) missed it too. The mapper already
reads it defensively (== "true", which is False on None), so this is
a safe default.

Surfaced by 7 failed modelling_e2e subtasks on portfolio 817.

datatypes/epc/schema/rdsap_schema_17_0.py

@@ -44,7 +44,9 @@ class SapHeating:
     instantaneous_wwhrs: Optional[InstantaneousWwhrs]
     main_heating_details: List[MainHeatingDetail]
     immersion_heating_type: Union[int, str]
-    has_fixed_air_conditioning: str
+    # Nested duplicate of the outer schema's has_fixed_air_conditioning
+    # (already Optional below) — some certs omit it here too.
+    has_fixed_air_conditioning: Optional[str] = None
     # ADR-0028: cylinder_insulation_type is absent in 308/1000 17.0 certs.
     cylinder_insulation_type: Optional[int] = None
     cylinder_thermostat: Optional[str] = None

datatypes/epc/schema/rdsap_schema_17_1.py

@@ -44,7 +44,9 @@ class SapHeating:
     instantaneous_wwhrs: Optional[InstantaneousWwhrs]
     main_heating_details: List[MainHeatingDetail]
     immersion_heating_type: Union[int, str]
-    has_fixed_air_conditioning: str
+    # Nested duplicate of the outer schema's has_fixed_air_conditioning
+    # (also made Optional below) — some certs omit it here too.
+    has_fixed_air_conditioning: Optional[str] = None
     # ADR-0028: 325/1000 omit cylinder_insulation_type — default it.
     cylinder_insulation_type: Optional[int] = None
     cylinder_thermostat: Optional[str] = None
@@ -247,7 +249,7 @@ class RdSapSchema17_1:
     hot_water_cost_potential: CostAmount
     renewable_heat_incentive: RenewableHeatIncentive
     energy_consumption_current: int
-    has_fixed_air_conditioning: str
+    has_fixed_air_conditioning: Optional[str] = None
     multiple_glazed_proportion: int
     calculation_software_version: str
     energy_consumption_potential: int

datatypes/epc/schema/rdsap_schema_18_0.py

@@ -44,7 +44,9 @@ class SapHeating:
     instantaneous_wwhrs: Optional[InstantaneousWwhrs]
     main_heating_details: List[MainHeatingDetail]
     immersion_heating_type: Union[int, str]
-    has_fixed_air_conditioning: str
+    # Nested duplicate of the outer schema's has_fixed_air_conditioning
+    # (also made Optional below) — some certs omit it here too.
+    has_fixed_air_conditioning: Optional[str] = None
     cylinder_insulation_type: Optional[int] = None
     cylinder_thermostat: Optional[str] = None
     secondary_fuel_type: Optional[int] = None
@@ -266,7 +268,7 @@ class RdSapSchema18_0:
     hot_water_cost_potential: CostAmount
     renewable_heat_incentive: RenewableHeatIncentive
     energy_consumption_current: int
-    has_fixed_air_conditioning: str
+    has_fixed_air_conditioning: Optional[str] = None
     multiple_glazed_proportion: int
     calculation_software_version: str
     energy_consumption_potential: int

datatypes/epc/schema/rdsap_schema_19_0.py

@@ -44,7 +44,9 @@ class SapHeating:
     instantaneous_wwhrs: Optional[InstantaneousWwhrs]
     main_heating_details: List[MainHeatingDetail]
     immersion_heating_type: Union[int, str]
-    has_fixed_air_conditioning: str
+    # Nested duplicate of the outer schema's has_fixed_air_conditioning
+    # (also made Optional below) — some certs omit it here too.
+    has_fixed_air_conditioning: Optional[str] = None
     cylinder_insulation_type: Optional[int] = None
     cylinder_thermostat: Optional[str] = None
     secondary_fuel_type: Optional[int] = None
@@ -281,7 +283,7 @@ class RdSapSchema19_0:
     # 19.0-specific block, absent in 713/1000 — Optional + default.
     windows_transmission_details: Optional[WindowsTransmissionDetails] = None
     energy_consumption_current: int
-    has_fixed_air_conditioning: str
+    has_fixed_air_conditioning: Optional[str] = None
     multiple_glazed_proportion: int
     calculation_software_version: str
     energy_consumption_potential: int

datatypes/epc/schema/rdsap_schema_20_0_0.py

@@ -56,7 +56,9 @@ class SapHeating:
     instantaneous_wwhrs: Optional[InstantaneousWwhrs]
     main_heating_details: List[MainHeatingDetail]
     immersion_heating_type: Union[int, str]
-    has_fixed_air_conditioning: str
+    # Nested duplicate of the outer schema's has_fixed_air_conditioning
+    # (already Optional below) — some certs omit it here too.
+    has_fixed_air_conditioning: Optional[str] = None
     cylinder_insulation_type: Optional[int] = None
     cylinder_thermostat: Optional[str] = None
     secondary_fuel_type: Optional[int] = None

datatypes/epc/schema/rdsap_schema_21_0_0.py

@@ -63,7 +63,9 @@ class SapHeating:
     water_heating_fuel: int
     main_heating_details: List[MainHeatingDetail]
     immersion_heating_type: Union[int, str]
-    has_fixed_air_conditioning: str
+    # Nested duplicate of the outer schema's has_fixed_air_conditioning
+    # (also made Optional below) — some certs omit it here too.
+    has_fixed_air_conditioning: Optional[str] = None
     instantaneous_wwhrs: Optional[InstantaneousWwhrs] = None
     # Real-API certs carry shower_outlets as a list, not the synthetic
     # single-object form; list elements are normalised to the wrapped
@@ -459,7 +461,7 @@ class RdSapSchema21_0_0:
     windows_transmission_details: Optional[WindowsTransmissionDetails] = None
     cfl_fixed_lighting_bulbs_count: Optional[int] = None
     energy_consumption_current: int
-    has_fixed_air_conditioning: str
+    has_fixed_air_conditioning: Optional[str] = None
     multiple_glazed_proportion: int
     calculation_software_version: str
     energy_consumption_potential: int

datatypes/epc/schema/rdsap_schema_21_0_1.py

@@ -1,4 +1,4 @@
-from dataclasses import dataclass
+from dataclasses import dataclass, field
 from typing import List, Optional, Union
 
 from .common import DescriptionV1, Measurement
@@ -64,7 +64,9 @@ class SapHeating:
     water_heating_fuel: int
     main_heating_details: List[MainHeatingDetail]
     immersion_heating_type: Union[int, str]
-    has_fixed_air_conditioning: str
+    # Nested duplicate of the outer schema's has_fixed_air_conditioning
+    # (also made Optional below) — some certs omit it here too.
+    has_fixed_air_conditioning: Optional[str] = None
     instantaneous_wwhrs: Optional[InstantaneousWwhrs] = None
     # Real-API certs carry shower_outlets as a list, not the synthetic single-object form;
     # accept both shapes so older fixtures keep parsing. List elements
@@ -510,7 +512,9 @@ class RdSapSchema21_0_1:
     renewable_heat_incentive: RenewableHeatIncentive
     draughtproofed_door_count: int
     energy_consumption_current: int
-    has_fixed_air_conditioning: str
+    # kw_only on just this field: the class isn't kw_only overall, and several
+    # required fields (calculation_software_version etc.) already follow it.
+    has_fixed_air_conditioning: Optional[str] = field(default=None, kw_only=True)
     calculation_software_version: str
     energy_consumption_potential: int
     environmental_impact_current: int