Revert renew_date to String for consistency with other date-only fields

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: Fivell

README.md

@@ -585,8 +585,8 @@ The SDK distinguishes between date-only and datetime fields:
   - `Proof.getCreatedAt()`, `Proof.getExpiresAt()`
   - `Order.getCreatedAt()`, `Identity.getCreatedAt()`, `Address.getCreatedAt()`, `VoiceInTrunk.getCreatedAt()`, `VoiceInTrunkGroup.getCreatedAt()`, `VoiceOutTrunk.getCreatedAt()`, `SharedCapacityGroup.getCreatedAt()`, `Export.getCreatedAt()`, `AddressVerification.getCreatedAt()`, `PermanentSupportingDocument.getCreatedAt()`
 - **Date-only fields** — deserialized as `LocalDate`:
-  - `Identity.getBirthDate()`, `CapacityPool.getRenewDate()`
-- **Billing range fields** (`DidOrderItem.getBilledFrom()`, `DidOrderItem.getBilledTo()`) remain as `String`.
+  - `Identity.getBirthDate()`
+- **Date-only fields kept as strings** (`CapacityPool.getRenewDate()`, `DidOrderItem.getBilledFrom()`, `DidOrderItem.getBilledTo()`) — remain as `String`.
 
 ```java
 Did did = client.dids().find("uuid").getData();

src/main/java/com/didww/sdk/resource/CapacityPool.java

@@ -5,7 +5,6 @@
 import com.github.jasminb.jsonapi.annotations.Type;
 import lombok.Getter;
 
-import java.time.LocalDate;
 import java.util.List;
 
 @Type("capacity_pools")
@@ -17,7 +16,7 @@ public class CapacityPool extends BaseResource {
     private String name;
 
     @JsonProperty(value = "renew_date", access = JsonProperty.Access.WRITE_ONLY)
-    private LocalDate renewDate;
+    private String renewDate;
 
     @JsonProperty("total_channels_count")
     private Integer totalChannelsCount;