Added additional validation to be sure that the value cannot be set to 0 which means unlimited level

common/data/src/main/java/org/thingsboard/server/common/data/cf/configuration/RelationQueryDynamicSourceConfiguration.java

@@ -45,6 +45,9 @@ public class RelationQueryDynamicSourceConfiguration implements CfArgumentDynami
 
     @Override
     public void validate() {
+        if (maxLevel < 1) {
+            throw new IllegalArgumentException("Relation query dynamic source configuration max relation level can't be less than 1!");
+        }
         if (maxLevel > 2) {
             throw new IllegalArgumentException("Relation query dynamic source configuration max relation level can't be greater than 2!");
         }

common/data/src/test/java/org/thingsboard/server/common/data/cf/configuration/RelationQueryDynamicSourceConfigurationTest.java

@@ -54,6 +54,18 @@ public class RelationQueryDynamicSourceConfigurationTest {
         assertThat(cfg.getType()).isEqualTo(CFArgumentDynamicSourceType.RELATION_QUERY);
     }
 
+    @Test
+    void validateShouldThrowWhenMaxLevelLessThanOne() {
+        var cfg = new RelationQueryDynamicSourceConfiguration();
+        cfg.setMaxLevel(0);
+        cfg.setDirection(EntitySearchDirection.FROM);
+        cfg.setRelationType(EntityRelation.CONTAINS_TYPE);
+
+        assertThatThrownBy(cfg::validate)
+                .isInstanceOf(IllegalArgumentException.class)
+                .hasMessage("Relation query dynamic source configuration max relation level can't be less than 1!");
+    }
+
     @Test
     void validateShouldThrowWhenMaxLevelGreaterThanTwo() {
         var cfg = new RelationQueryDynamicSourceConfiguration();