PushJson/PopJson did not work correctly, if null beans were involved

ebean-core/src/main/java/io/ebeaninternal/server/type/ScalarTypeJsonObjectMapper.java

@@ -80,11 +80,11 @@ class ScalarTypeJsonObjectMapper {
     @Override
     public Object read(DataReader reader) throws SQLException {
       String json = reader.getString();
+      // pushJson such that we MD5 and store on EntityBeanIntercept later
+      reader.pushJson(json);
       if (json == null || json.isEmpty()) {
         return null;
       }
-      // pushJson such that we MD5 and store on EntityBeanIntercept later
-      reader.pushJson(json);
       try {
         return objectReader.readValue(json, deserType);
       } catch (IOException e) {

ebean-core/src/test/java/org/tests/json/TestDbJson_Jackson3.java

@@ -10,6 +10,7 @@ import io.ebeantest.LoggedSql;
 import org.junit.Test;
 import org.tests.model.json.EBasicJsonJackson3;
 import org.tests.model.json.EBasicJsonList;
+import org.tests.model.json.EBasicJsonMulti;
 import org.tests.model.json.PlainBean;
 import org.tests.model.json.PlainBeanDirtyAware;
 
@@ -221,6 +222,21 @@ public class TestDbJson_Jackson3 extends BaseTestCase {
 
     LoggedSql.stop();
   }
+  
+  @Test
+  public void push_pop_test() {
+    
+    EBasicJsonMulti bean = new EBasicJsonMulti();
+    bean.setPlainValue2(new PlainBeanDirtyAware("x", 42));
+    bean.save();
+    
+    bean = DB.find(EBasicJsonMulti.class, bean.getId());
+    bean.setPlainValue1(null); // already null
+    bean.setPlainValue2(null);
+    bean.setPlainValue3(null); // already null
+    BeanState state = DB.getBeanState(bean);
+    assertThat(state.getDirtyValues()).hasSize(1).containsKey("plainValue2");
+  }
 
   private void expectedSql(int i, String s) {
     assertThat(LoggedSql.collect().get(i)).contains(s);

ebean-core/src/test/java/org/tests/model/json/EBasicJsonMulti.java

@@ -0,0 +1,81 @@
+package org.tests.model.json;
+
+import io.ebean.Model;
+import io.ebean.annotation.DbJson;
+import io.ebean.annotation.MutationDetection;
+
+import javax.persistence.Entity;
+import javax.persistence.Id;
+import javax.persistence.Version;
+
+import static io.ebean.annotation.MutationDetection.NONE;
+import static io.ebean.annotation.MutationDetection.SOURCE;
+
+@Entity
+public class EBasicJsonMulti extends Model {
+
+  @Id
+  Long id;
+
+  String name;
+
+  @DbJson(length = 500, mutationDetection = SOURCE)
+  PlainBeanDirtyAware plainValue1;
+
+  @DbJson(length = 500, mutationDetection = SOURCE)
+  PlainBeanDirtyAware plainValue2;
+
+  @DbJson(length = 500, mutationDetection = SOURCE)
+  PlainBeanDirtyAware plainValue3;
+
+  @Version
+  long version;
+
+  public Long getId() {
+    return id;
+  }
+
+  public void setId(Long id) {
+    this.id = id;
+  }
+
+  public String getName() {
+    return name;
+  }
+
+  public void setName(String name) {
+    this.name = name;
+  }
+
+  public PlainBeanDirtyAware getPlainValue1() {
+    return plainValue1;
+  }
+
+  public void setPlainValue1(PlainBeanDirtyAware plainValue1) {
+    this.plainValue1 = plainValue1;
+  }
+
+  public PlainBeanDirtyAware getPlainValue2() {
+    return plainValue2;
+  }
+
+  public void setPlainValue2(PlainBeanDirtyAware plainValue2) {
+    this.plainValue2 = plainValue2;
+  }
+
+  public PlainBeanDirtyAware getPlainValue3() {
+    return plainValue3;
+  }
+
+  public void setPlainValue3(PlainBeanDirtyAware plainValue3) {
+    this.plainValue3 = plainValue3;
+  }
+
+  public long getVersion() {
+    return version;
+  }
+
+  public void setVersion(long version) {
+    this.version = version;
+  }
+}