polish(validation): replace requireNonNull with bean validation (#10, #15)

docs/translation-rules.md

@@ -110,6 +110,15 @@ Never persist both forms.
   of the commarea (e.g. `INQCUST-CUSTNO` → `customerNumber`).
 - Validation via `jakarta.validation` annotations; constraint violations
   yield HTTP 400 from the `@ControllerAdvice`.
+- Required fields on request-DTO records are expressed exclusively through
+  `@NotNull` (and `@NotBlank` for non-blank strings such as customer
+  name/address) on the record components, with `@Valid` on the controller
+  parameter and on every nested DTO/Key reference. Do **not** put
+  `Objects.requireNonNull(...)` checks inside the canonical constructor of
+  a request DTO: those throw `NullPointerException` during Jackson
+  deserialization, bypass `MethodArgumentNotValidException`, and surface
+  as a 500 (`UNEX`) instead of the intended 400. Issues #10 and #15 are
+  the empirical source for this rule.
 - A "not found" commarea result (e.g. `INQCUST-INQ-FAIL-CD = '1'`) maps to
   HTTP 404 with a `{ failCode, message }` body, **not** an exception.
 - Hard failures (commarea-style abend) map to HTTP 500 with a structured

src/main/java/com/augment/cbsa/service/CrecustService.java

@@ -37,7 +37,7 @@ public class CrecustService {
     private static final int REVIEW_DATE_BOUND = 20;
     private static final long CREDIT_AGENCY_REPLY_WINDOW_SECONDS = 3;
     private static final List<String> VALID_TITLES = List.of(
-            "Professor", "Mr", "Mrs", "Miss", "Ms", "Dr", "Drs", "Lord", "Sir", "Lady", ""
+            "Professor", "Mr", "Mrs", "Miss", "Ms", "Dr", "Drs", "Lord", "Sir", "Lady"
     );
 
     private final CrecustRepository crecustRepository;

src/main/java/com/augment/cbsa/web/creacc/dto/CreaccCommareaRequestDto.java

@@ -10,7 +10,6 @@
 import jakarta.validation.constraints.NotNull;
 import jakarta.validation.constraints.Size;
 import java.math.BigDecimal;
-import java.util.Objects;
 
 public record CreaccCommareaRequestDto(
         @JsonProperty("CommEyecatcher")
@@ -83,14 +82,4 @@ public record CreaccCommareaRequestDto(
         @Size(max = 1)
         String commFailCode
 ) {
-
-    public CreaccCommareaRequestDto {
-        Objects.requireNonNull(commCustno, "commCustno must not be null");
-        Objects.requireNonNull(commKey, "commKey must not be null");
-        Objects.requireNonNull(commAccType, "commAccType must not be null");
-        Objects.requireNonNull(commIntRt, "commIntRt must not be null");
-        Objects.requireNonNull(commOverdrLim, "commOverdrLim must not be null");
-        Objects.requireNonNull(commAvailBal, "commAvailBal must not be null");
-        Objects.requireNonNull(commActBal, "commActBal must not be null");
-    }
 }

src/main/java/com/augment/cbsa/web/creacc/dto/CreaccKeyDto.java

@@ -5,7 +5,6 @@
 import jakarta.validation.constraints.Min;
 import jakarta.validation.constraints.NotNull;
 import jakarta.validation.constraints.Pattern;
-import java.util.Objects;
 
 public record CreaccKeyDto(
         @JsonProperty("CommSortcode")
@@ -19,9 +18,4 @@ public record CreaccKeyDto(
         @Max(99_999_999)
         Long commNumber
 ) {
-
-    public CreaccKeyDto {
-        Objects.requireNonNull(commSortcode, "commSortcode must not be null");
-        Objects.requireNonNull(commNumber, "commNumber must not be null");
-    }
 }

src/main/java/com/augment/cbsa/web/creacc/dto/CreaccRequestDto.java

@@ -3,16 +3,11 @@
 import com.fasterxml.jackson.annotation.JsonProperty;
 import jakarta.validation.Valid;
 import jakarta.validation.constraints.NotNull;
-import java.util.Objects;
 
 public record CreaccRequestDto(
         @JsonProperty("CreAcc")
         @Valid
         @NotNull
         CreaccCommareaRequestDto creAcc
 ) {
-
-    public CreaccRequestDto {
-        Objects.requireNonNull(creAcc, "creAcc must not be null");
-    }
 }

src/main/java/com/augment/cbsa/web/crecust/dto/CrecustCommareaRequestDto.java

@@ -4,9 +4,9 @@
 import jakarta.validation.Valid;
 import jakarta.validation.constraints.Max;
 import jakarta.validation.constraints.Min;
+import jakarta.validation.constraints.NotBlank;
 import jakarta.validation.constraints.NotNull;
 import jakarta.validation.constraints.Size;
-import java.util.Objects;
 
 public record CrecustCommareaRequestDto(
         @JsonProperty("CommEyecatcher")
@@ -19,7 +19,7 @@ public record CrecustCommareaRequestDto(
         CrecustKeyDto commKey,
 
         @JsonProperty("CommName")
-        @NotNull
+        @NotBlank
         @Size(max = 60)
         String commName,
 
@@ -52,11 +52,4 @@ public record CrecustCommareaRequestDto(
         @Size(max = 1)
         String commFailCode
 ) {
-
-    public CrecustCommareaRequestDto {
-        Objects.requireNonNull(commKey, "commKey must not be null");
-        Objects.requireNonNull(commName, "commName must not be null");
-        Objects.requireNonNull(commAddress, "commAddress must not be null");
-        Objects.requireNonNull(commDateOfBirth, "commDateOfBirth must not be null");
-    }
 }

src/main/java/com/augment/cbsa/web/crecust/dto/CrecustKeyDto.java

@@ -5,7 +5,6 @@
 import jakarta.validation.constraints.Min;
 import jakarta.validation.constraints.NotNull;
 import jakarta.validation.constraints.Pattern;
-import java.util.Objects;
 
 public record CrecustKeyDto(
         @JsonProperty("CommSortcode")
@@ -19,9 +18,4 @@ public record CrecustKeyDto(
         @Max(9_999_999_999L)
         Long commNumber
 ) {
-
-    public CrecustKeyDto {
-        Objects.requireNonNull(commSortcode, "commSortcode must not be null");
-        Objects.requireNonNull(commNumber, "commNumber must not be null");
-    }
 }

src/main/java/com/augment/cbsa/web/crecust/dto/CrecustRequestDto.java

@@ -3,16 +3,11 @@
 import com.fasterxml.jackson.annotation.JsonProperty;
 import jakarta.validation.Valid;
 import jakarta.validation.constraints.NotNull;
-import java.util.Objects;
 
 public record CrecustRequestDto(
         @JsonProperty("CreCust")
         @Valid
         @NotNull
         CrecustCommareaRequestDto creCust
 ) {
-
-    public CrecustRequestDto {
-        Objects.requireNonNull(creCust, "creCust must not be null");
-    }
 }

src/main/java/com/augment/cbsa/web/dbcrfun/dto/DbcrfunRequestDto.java

@@ -3,16 +3,11 @@
 import com.fasterxml.jackson.annotation.JsonProperty;
 import jakarta.validation.Valid;
 import jakarta.validation.constraints.NotNull;
-import java.util.Objects;
 
 public record DbcrfunRequestDto(
         @JsonProperty("PAYDBCR")
         @Valid
         @NotNull
         DbcrfunCommareaRequestDto paydbcr
 ) {
-
-    public DbcrfunRequestDto {
-        Objects.requireNonNull(paydbcr, "paydbcr must not be null");
-    }
 }

src/main/java/com/augment/cbsa/web/delcus/dto/DelcusRequestDto.java

@@ -3,16 +3,11 @@
 import com.fasterxml.jackson.annotation.JsonProperty;
 import jakarta.validation.Valid;
 import jakarta.validation.constraints.NotNull;
-import java.util.Objects;
 
 public record DelcusRequestDto(
         @JsonProperty("DelCus")
         @Valid
         @NotNull
         DelcusCommareaRequestDto delCus
 ) {
-
-    public DelcusRequestDto {
-        Objects.requireNonNull(delCus, "delCus must not be null");
-    }
 }

src/main/java/com/augment/cbsa/web/updcust/dto/UpdcustCommareaRequestDto.java

@@ -3,10 +3,10 @@
 import com.fasterxml.jackson.annotation.JsonProperty;
 import jakarta.validation.constraints.Max;
 import jakarta.validation.constraints.Min;
+import jakarta.validation.constraints.NotBlank;
 import jakarta.validation.constraints.NotNull;
 import jakarta.validation.constraints.Pattern;
 import jakarta.validation.constraints.Size;
-import java.util.Objects;
 
 public record UpdcustCommareaRequestDto(
         @JsonProperty("CommEye")
@@ -24,12 +24,12 @@ public record UpdcustCommareaRequestDto(
         String commCustno,
 
         @JsonProperty("CommName")
-        @NotNull
+        @NotBlank
         @Size(max = 60)
         String commName,
 
         @JsonProperty("CommAddress")
-        @NotNull
+        @NotBlank
         @Size(max = 160)
         String commAddress,
 
@@ -59,14 +59,4 @@ public record UpdcustCommareaRequestDto(
         @Size(max = 1)
         String commUpdFailCd
 ) {
-
-    public UpdcustCommareaRequestDto {
-        Objects.requireNonNull(commScode, "commScode must not be null");
-        Objects.requireNonNull(commCustno, "commCustno must not be null");
-        Objects.requireNonNull(commName, "commName must not be null");
-        Objects.requireNonNull(commAddress, "commAddress must not be null");
-        Objects.requireNonNull(commDob, "commDob must not be null");
-        Objects.requireNonNull(commCreditScore, "commCreditScore must not be null");
-        Objects.requireNonNull(commCsReviewDate, "commCsReviewDate must not be null");
-    }
 }

src/main/java/com/augment/cbsa/web/updcust/dto/UpdcustRequestDto.java

@@ -3,16 +3,11 @@
 import com.fasterxml.jackson.annotation.JsonProperty;
 import jakarta.validation.Valid;
 import jakarta.validation.constraints.NotNull;
-import java.util.Objects;
 
 public record UpdcustRequestDto(
         @JsonProperty("UpdCust")
         @Valid
         @NotNull
         UpdcustCommareaRequestDto updCust
 ) {
-
-    public UpdcustRequestDto {
-        Objects.requireNonNull(updCust, "updCust must not be null");
-    }
 }

src/test/java/com/augment/cbsa/service/CrecustServiceUnitTest.java

@@ -62,6 +62,15 @@ void rejectsInvalidCustomerTitles() {
         verifyNoInteractions(creditAgencyService, crecustRepository, reviewDateRandom);
     }
 
+    @Test
+    void rejectsBlankCustomerNamesAtTitleValidation() {
+        CrecustResult result = crecustService.create(new CrecustRequest("   ", "1 Main Street", 1012000));
+
+        assertThat(result.creationSuccess()).isFalse();
+        assertThat(result.failCode()).isEqualTo("T");
+        verifyNoInteractions(creditAgencyService, crecustRepository, reviewDateRandom);
+    }
+
     @Test
     void rejectsDatesEarlierThan1601() {
         CrecustResult result = crecustService.create(new CrecustRequest("Dr Example", "1 Main Street", 1011500));

src/test/java/com/augment/cbsa/web/crecust/CrecustControllerWebMvcTest.java

@@ -96,6 +96,28 @@ void requestValidationFailuresRemainProblemDetails() throws Exception {
                 .andExpect(jsonPath("$.title").value("Validation failed"));
     }
 
+    @Test
+    void missingRequiredFieldReturnsBadRequest() throws Exception {
+        // CommName omitted entirely; bean validation must reject with 400 rather
+        // than letting a constructor NPE escalate to a 500 abend.
+        mockMvc.perform(post("/api/v1/crecust/insert")
+                        .contentType(APPLICATION_JSON)
+                        .content("""
+                                {"CreCust":{"CommKey":{"CommSortcode":"000000","CommNumber":0},"CommAddress":"1 Main Street","CommDateOfBirth":10012000}}
+                                """))
+                .andExpect(status().isBadRequest())
+                .andExpect(jsonPath("$.title").value("Validation failed"));
+    }
+
+    @Test
+    void blankCommNameReturnsBadRequest() throws Exception {
+        mockMvc.perform(post("/api/v1/crecust/insert")
+                        .contentType(APPLICATION_JSON)
+                        .content(requestJson("   ", "1 Main Street", 10_01_2000)))
+                .andExpect(status().isBadRequest())
+                .andExpect(jsonPath("$.title").value("Validation failed"));
+    }
+
     @Test
     void redactsAbendExceptionMessageFromResponseBody() throws Exception {
         when(crecustService.create(new CrecustRequest("Dr Alice Example", "1 Main Street", 10_01_2000)))