fix: 根据修复意见修改，字段被显式设为 None 时的类型兼容，如Risks: null 的反序列化

Author: ylsssssss

volcenginesdkllmshield/api/llm_shield_sdk_v2.py

@@ -107,6 +107,10 @@ class RiskV2(BaseModel):
     prob: Optional[float] = Field(None, alias="Prob")
     matches: List[RiskMatchV2] = Field([], alias="Matches")
 
+    @field_validator('matches', mode="before")
+    def convert_risk_matches_none_to_list(cls, value):
+        return [] if value is None else value
+
     class Config:
         populate_by_name = True
 
@@ -130,6 +134,10 @@ class PermitV2(BaseModel):
     prob: Optional[float] = Field(None, alias="Prob")
     matches: List[PermitMatchV2] = Field([], alias="Matches")
 
+    @field_validator('matches', mode="before")
+    def convert_permit_matches_none_to_list(cls, value):
+        return [] if value is None else value
+
     class Config:
         populate_by_name = True
 
@@ -176,6 +184,10 @@ class DecisionV2(BaseModel):
     decision_strategy_id: Optional[str] = Field(None, alias="DecisionStrategyID")
     hit_strategy_ids: List[str] = Field([], alias="HitStrategyIDs")
 
+    @field_validator('hit_strategy_ids', mode="before")
+    def convert_hit_strategies_none_to_list(cls, value):
+        return [] if value is None else value
+
     class Config:
         populate_by_name = True