killbill-memoizeit

diff --git a/account/src/main/java/org/killbill/billing/account/dao/AccountModelDao.java b/account/src/main/java/org/killbill/billing/account/dao/AccountModelDao.java
index 353812e..ac70362 100644
--- a/account/src/main/java/org/killbill/billing/account/dao/AccountModelDao.java
+++ b/account/src/main/java/org/killbill/billing/account/dao/AccountModelDao.java
@@ -74,7 +74,7 @@ public class AccountModelDao extends EntityModelDaoBase implements EntityModelDa
         this.currency = currency;
         this.billingCycleDayLocal = billingCycleDayLocal;
         this.paymentMethodId = paymentMethodId;
-        this.timeZone = timeZone;
+        this.timeZone = MoreObjects.firstNonNull(timeZone, DateTimeZone.UTC);
         this.locale = locale;
         this.address1 = address1;
         this.address2 = address2;

diff --git a/account/src/main/resources/org/killbill/billing/account/ddl.sql b/account/src/main/resources/org/killbill/billing/account/ddl.sql
index 50227ce..01158e4 100644
--- a/account/src/main/resources/org/killbill/billing/account/ddl.sql
+++ b/account/src/main/resources/org/killbill/billing/account/ddl.sql
@@ -11,7 +11,7 @@ CREATE TABLE accounts (
     currency varchar(3) DEFAULT NULL,
     billing_cycle_day_local int DEFAULT NULL,
     payment_method_id varchar(36) DEFAULT NULL,
-    time_zone varchar(50) DEFAULT NULL,
+    time_zone varchar(50) NOT NULL,
     locale varchar(5) DEFAULT NULL,
     address1 varchar(100) DEFAULT NULL,
     address2 varchar(100) DEFAULT NULL,
@@ -46,7 +46,7 @@ CREATE TABLE account_history (
     currency varchar(3) DEFAULT NULL,
     billing_cycle_day_local int DEFAULT NULL,
     payment_method_id varchar(36) DEFAULT NULL,
-    time_zone varchar(50) DEFAULT NULL,
+    time_zone varchar(50) NOT NULL,
     locale varchar(5) DEFAULT NULL,
     address1 varchar(100) DEFAULT NULL,
     address2 varchar(100) DEFAULT NULL,

diff --git a/account/src/test/java/org/killbill/billing/account/dao/TestAccountDao.java b/account/src/test/java/org/killbill/billing/account/dao/TestAccountDao.java
index 70a3947..fc3fece 100644
--- a/account/src/test/java/org/killbill/billing/account/dao/TestAccountDao.java
+++ b/account/src/test/java/org/killbill/billing/account/dao/TestAccountDao.java
@@ -76,6 +76,9 @@ public class TestAccountDao extends AccountTestSuiteWithEmbeddedDB {
 
         // Verify a default external key was set
         Assert.assertEquals(retrievedAccount.getExternalKey(), retrievedAccount.getId().toString());
+
+        // Verify a default time zone was set
+        Assert.assertEquals(retrievedAccount.getTimeZone(), DateTimeZone.UTC);
     }
 
     @Test(groups = "slow", description = "Test Account: basic DAO calls")