diff --git a/client/src/main/com/sinch/sdk/domains/numbers/adapters/NumbersService.java b/client/src/main/com/sinch/sdk/domains/numbers/adapters/NumbersService.java
index 41ba55b1..ce2f1788 100644
--- a/client/src/main/com/sinch/sdk/domains/numbers/adapters/NumbersService.java
+++ b/client/src/main/com/sinch/sdk/domains/numbers/adapters/NumbersService.java
@@ -3,10 +3,10 @@
 import com.sinch.sdk.auth.adapters.BasicAuthManager;
 import com.sinch.sdk.core.http.AuthManager;
 import com.sinch.sdk.core.http.HttpClient;
+import com.sinch.sdk.core.utils.StringUtil;
 import com.sinch.sdk.models.Configuration;
 import java.util.AbstractMap;
 import java.util.Map;
-import java.util.Objects;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
@@ -25,9 +25,9 @@ public class NumbersService implements com.sinch.sdk.domains.numbers.NumbersServ
 
   public NumbersService(Configuration configuration, HttpClient httpClient) {
 
-    Objects.requireNonNull(configuration.getKeyId(), "'keyId' cannot be null");
-    Objects.requireNonNull(configuration.getKeySecret(), "'keySecret' cannot be null");
-    Objects.requireNonNull(configuration.getProjectId(), "'projectId' cannot be null");
+    StringUtil.requireNonEmpty(configuration.getKeyId(), "'keyId' must be defined");
+    StringUtil.requireNonEmpty(configuration.getKeySecret(), "'keySecret' must be defined");
+    StringUtil.requireNonEmpty(configuration.getProjectId(), "'projectId' must be defined");
 
     this.configuration = configuration;
     this.httpClient = httpClient;
diff --git a/client/src/main/com/sinch/sdk/domains/sms/adapters/SMSService.java b/client/src/main/com/sinch/sdk/domains/sms/adapters/SMSService.java
index ef3a39f5..813010ea 100644
--- a/client/src/main/com/sinch/sdk/domains/sms/adapters/SMSService.java
+++ b/client/src/main/com/sinch/sdk/domains/sms/adapters/SMSService.java
@@ -4,6 +4,7 @@
 import com.sinch.sdk.core.http.AuthManager;
 import com.sinch.sdk.core.http.HttpClient;
 import com.sinch.sdk.core.http.HttpMapper;
+import com.sinch.sdk.core.utils.StringUtil;
 import com.sinch.sdk.domains.sms.BatchesService;
 import com.sinch.sdk.domains.sms.DeliveryReportsService;
 import com.sinch.sdk.domains.sms.InboundsService;
@@ -11,7 +12,6 @@
 import com.sinch.sdk.models.Configuration;
 import java.util.AbstractMap;
 import java.util.Map;
-import java.util.Objects;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
@@ -31,9 +31,9 @@ public SMSService(Configuration configuration, HttpClient httpClient) {
 
     // Currently, we are only supporting  unified credentials: ensure credentials are
     // defined
-    Objects.requireNonNull(configuration.getKeyId(), "'keyId' cannot be null");
-    Objects.requireNonNull(configuration.getKeySecret(), "'keySecret' cannot be null");
-    Objects.requireNonNull(configuration.getProjectId(), "'projectId' cannot be null");
+    StringUtil.requireNonEmpty(configuration.getKeyId(), "'keyId' must be defined");
+    StringUtil.requireNonEmpty(configuration.getKeySecret(), "'keySecret' must be defined");
+    StringUtil.requireNonEmpty(configuration.getProjectId(), "'projectId' must be defined");
 
     this.configuration = configuration;
     this.httpClient = httpClient;
diff --git a/client/src/main/com/sinch/sdk/domains/verification/adapters/VerificationService.java b/client/src/main/com/sinch/sdk/domains/verification/adapters/VerificationService.java
index e8c48736..a310c251 100644
--- a/client/src/main/com/sinch/sdk/domains/verification/adapters/VerificationService.java
+++ b/client/src/main/com/sinch/sdk/domains/verification/adapters/VerificationService.java
@@ -5,12 +5,12 @@
 import com.sinch.sdk.core.exceptions.ApiAuthException;
 import com.sinch.sdk.core.http.AuthManager;
 import com.sinch.sdk.core.http.HttpClient;
+import com.sinch.sdk.core.utils.StringUtil;
 import com.sinch.sdk.domains.verification.StatusService;
 import com.sinch.sdk.domains.verification.VerificationsService;
 import com.sinch.sdk.domains.verification.WebHooksService;
 import com.sinch.sdk.models.Configuration;
 import java.util.Map;
-import java.util.Objects;
 import java.util.TreeMap;
 
 public class VerificationService implements com.sinch.sdk.domains.verification.VerificationService {
@@ -33,9 +33,10 @@ public VerificationService(Configuration configuration, HttpClient httpClient) {
 
     // Currently, we are not supporting unified credentials: ensure application credentials are
     // defined
-    Objects.requireNonNull(configuration.getApplicationKey(), "'applicationKey' cannot be null");
-    Objects.requireNonNull(
-        configuration.getApplicationSecret(), "'applicationSecret' cannot be null");
+    StringUtil.requireNonEmpty(
+        configuration.getApplicationKey(), "'applicationKey' must be defined");
+    StringUtil.requireNonEmpty(
+        configuration.getApplicationSecret(), "'applicationSecret' must be defined");
 
     this.configuration = configuration;
     this.httpClient = httpClient;
diff --git a/client/src/test/java/com/sinch/sdk/domains/numbers/adapters/NumbersServiceTest.java b/client/src/test/java/com/sinch/sdk/domains/numbers/adapters/NumbersServiceTest.java
index 7330b847..e8c2ea0b 100644
--- a/client/src/test/java/com/sinch/sdk/domains/numbers/adapters/NumbersServiceTest.java
+++ b/client/src/test/java/com/sinch/sdk/domains/numbers/adapters/NumbersServiceTest.java
@@ -18,7 +18,7 @@ void doNotAcceptNullKey() {
         Configuration.builder().setKeyId(null).setKeySecret("foo").setProjectId("foo").build();
     Exception exception =
         assertThrows(
-            NullPointerException.class, () -> new NumbersService(configuration, httpClient));
+            IllegalArgumentException.class, () -> new NumbersService(configuration, httpClient));
     assertTrue(exception.getMessage().contains("keyId"));
   }
 
@@ -28,7 +28,7 @@ void doNotAcceptNullKeySecret() {
         Configuration.builder().setKeyId("foo").setKeySecret(null).setProjectId("foo").build();
     Exception exception =
         assertThrows(
-            NullPointerException.class, () -> new NumbersService(configuration, httpClient));
+            IllegalArgumentException.class, () -> new NumbersService(configuration, httpClient));
     assertTrue(exception.getMessage().contains("keySecret"));
   }
 
@@ -38,7 +38,7 @@ void doNotAcceptNullProject() {
         Configuration.builder().setKeyId("foo").setKeySecret("foo").setProjectId(null).build();
     Exception exception =
         assertThrows(
-            NullPointerException.class, () -> new NumbersService(configuration, httpClient));
+            IllegalArgumentException.class, () -> new NumbersService(configuration, httpClient));
     assertTrue(exception.getMessage().contains("projectId"));
   }
 }
diff --git a/client/src/test/java/com/sinch/sdk/domains/sms/adapters/SMSServiceTest.java b/client/src/test/java/com/sinch/sdk/domains/sms/adapters/SMSServiceTest.java
index 51de3bf4..8caa8614 100644
--- a/client/src/test/java/com/sinch/sdk/domains/sms/adapters/SMSServiceTest.java
+++ b/client/src/test/java/com/sinch/sdk/domains/sms/adapters/SMSServiceTest.java
@@ -17,7 +17,8 @@ void doNotAcceptNullKey() {
     Configuration configuration =
         Configuration.builder().setKeyId(null).setKeySecret("foo").setProjectId("foo").build();
     Exception exception =
-        assertThrows(NullPointerException.class, () -> new SMSService(configuration, httpClient));
+        assertThrows(
+            IllegalArgumentException.class, () -> new SMSService(configuration, httpClient));
     assertTrue(exception.getMessage().contains("keyId"));
   }
 
@@ -26,7 +27,8 @@ void doNotAcceptNullKeySecret() {
     Configuration configuration =
         Configuration.builder().setKeyId("foo").setKeySecret(null).setProjectId("foo").build();
     Exception exception =
-        assertThrows(NullPointerException.class, () -> new SMSService(configuration, httpClient));
+        assertThrows(
+            IllegalArgumentException.class, () -> new SMSService(configuration, httpClient));
     assertTrue(exception.getMessage().contains("keySecret"));
   }
 
@@ -35,7 +37,8 @@ void doNotAcceptNullProject() {
     Configuration configuration =
         Configuration.builder().setKeyId("foo").setKeySecret("foo").setProjectId(null).build();
     Exception exception =
-        assertThrows(NullPointerException.class, () -> new SMSService(configuration, httpClient));
+        assertThrows(
+            IllegalArgumentException.class, () -> new SMSService(configuration, httpClient));
     assertTrue(exception.getMessage().contains("projectId"));
   }
 }
diff --git a/client/src/test/java/com/sinch/sdk/domains/verification/adapters/VerificationServiceTest.java b/client/src/test/java/com/sinch/sdk/domains/verification/adapters/VerificationServiceTest.java
index bb021686..0547370c 100644
--- a/client/src/test/java/com/sinch/sdk/domains/verification/adapters/VerificationServiceTest.java
+++ b/client/src/test/java/com/sinch/sdk/domains/verification/adapters/VerificationServiceTest.java
@@ -18,7 +18,8 @@ void doNotAcceptNullApplicationKey() {
         Configuration.builder().setApplicationKey(null).setApplicationSecret("foo secret").build();
     Exception exception =
         assertThrows(
-            NullPointerException.class, () -> new VerificationService(configuration, httpClient));
+            IllegalArgumentException.class,
+            () -> new VerificationService(configuration, httpClient));
     assertTrue(exception.getMessage().contains("applicationKey"));
   }
 
@@ -28,7 +29,8 @@ void doNotAcceptNullApplicationSecret() {
         Configuration.builder().setApplicationKey("foo key").setApplicationSecret(null).build();
     Exception exception =
         assertThrows(
-            NullPointerException.class, () -> new VerificationService(configuration, httpClient));
+            IllegalArgumentException.class,
+            () -> new VerificationService(configuration, httpClient));
     assertTrue(exception.getMessage().contains("applicationSecret"));
   }
 }
diff --git a/core/src/main/com/sinch/sdk/core/utils/StringUtil.java b/core/src/main/com/sinch/sdk/core/utils/StringUtil.java
index ae515990..cb9c2b88 100644
--- a/core/src/main/com/sinch/sdk/core/utils/StringUtil.java
+++ b/core/src/main/com/sinch/sdk/core/utils/StringUtil.java
@@ -13,4 +13,21 @@ public class StringUtil {
   public static boolean isEmpty(String value) {
     return (null == value || value.trim().isEmpty());
   }
+
+  /**
+   * Checks that the specified object reference is not {@code null} not an empty string. This method
+   * is designed primarily for doing parameter validation in methods and constructors
+   *
+   * @param obj the object reference to check for nullity
+   * @param message detail message to be used in the event that a {@code IllegalArgumentException}
+   *     is thrown
+   * @return {@code obj} if not {@code null} nor empty
+   * @throws IllegalArgumentException if {@code obj} is {@code null} or {@code empty}
+   */
+  public static String requireNonEmpty(String obj, String message) {
+    if (isEmpty(obj)) {
+      throw new IllegalArgumentException(message);
+    }
+    return obj;
+  }
 }