UPD. Refactoring and changes according to comments.

Signed-off-by: Oleksandra Matviienko <al.zzzeebra@gmail.com>

dao/src/main/java/org/thingsboard/server/dao/service/Validator.java

@@ -193,9 +193,8 @@ public class Validator {
         if (ids == null || ids.isEmpty()) {
             throw new IncorrectParameterException(errorMessageFunction.apply(ids));
         } else {
-            Supplier<String> errorMessageSupplier = () -> errorMessageFunction.apply(ids);
             for (UUIDBased id : ids) {
-                validateId(id, errorMessageSupplier);
+                validateId(id, errorMessageFunction.apply(ids));
             }
         }
     }
@@ -245,18 +244,4 @@ public class Validator {
             throw new IncorrectParameterException(errorMessage);
         }
     }
-
-    /**
-     * This method validate list of <code>UUIDBased</code> ids. If at least one of the ids is null than throw
-     * <code>IncorrectParameterException</code> exception
-     *
-     * @param reference            the list of ids
-     * @param errorMessageFunction the error message for exception that applies reference
-     */
-    public static void checkNotNull(Object reference, Function<Object, String> errorMessageFunction) {
-        if (reference == null) {
-            throw new IncorrectParameterException(errorMessageFunction.apply(reference));
-        }
-    }
-
 }

dao/src/test/java/org/thingsboard/server/dao/service/ValidatorTest.java

@@ -105,11 +105,9 @@ class ValidatorTest {
     }
 
     @Test
-    void validateIds() {
-
+    void validateIdsTest() {
         List<? extends UUIDBased> list = List.of(goodDeviceId);
         Validator.validateIds( list, ids -> "Incorrect Id " + ids);
-        Validator.validateId(list.get(0), id -> "Incorrect Id " + id);
 
         assertThatThrownBy(() -> Validator.validateIds(null, id -> "Incorrect Ids " + id))
                 .as("Ids are null")
@@ -134,6 +132,7 @@ class ValidatorTest {
                 .hasMessageContaining("null");
 
     }
+
     @Test
     void validateIdSupplier() {
         Validator.validateId(TenantId.SYS_TENANT_ID, () -> "Incorrect Id null");
@@ -149,16 +148,4 @@ class ValidatorTest {
                 .isInstanceOf(IncorrectParameterException.class)
                 .hasMessageContaining("Incorrect Id null");
     }
-
-    @Test
-    void checkNotNullTest() {
-        Validator.checkNotNull("notnull", reference -> "Incorrect reference " + reference);
-
-        assertThatThrownBy(() -> Validator.checkNotNull(null, reference -> "Incorrect reference " + reference))
-                .as("Reference is null")
-                .isInstanceOf(IncorrectParameterException.class)
-                .hasMessageContaining("Incorrect reference null");
-
-    }
-
 }