diff --git a/src/main/java/org/javarosa/core/model/data/BooleanData.java b/src/main/java/org/javarosa/core/model/data/BooleanData.java
index d05fe8433..519b16295 100644
--- a/src/main/java/org/javarosa/core/model/data/BooleanData.java
+++ b/src/main/java/org/javarosa/core/model/data/BooleanData.java
@@ -64,7 +64,7 @@ public String getDisplayText() {
 
 
     @Override
-    public void setValue(Object o) {
+    public void setValue(@NotNull Object o) {
         data = (Boolean) o;
     }
 
diff --git a/src/main/java/org/javarosa/core/model/data/DateData.java b/src/main/java/org/javarosa/core/model/data/DateData.java
index faf3cece8..102ab9c2f 100644
--- a/src/main/java/org/javarosa/core/model/data/DateData.java
+++ b/src/main/java/org/javarosa/core/model/data/DateData.java
@@ -61,7 +61,7 @@ public IAnswerData clone () {
     }
 
     @Override
-    public void setValue (Object o) {
+    public void setValue (@NotNull Object o) {
         //Should not ever be possible to set this to a null value
         if(o == null) {
             throw new NullPointerException("Attempt to set an IAnswerData class to null.");
diff --git a/src/main/java/org/javarosa/core/model/data/DateTimeData.java b/src/main/java/org/javarosa/core/model/data/DateTimeData.java
index 39b8f5399..c91e1b511 100644
--- a/src/main/java/org/javarosa/core/model/data/DateTimeData.java
+++ b/src/main/java/org/javarosa/core/model/data/DateTimeData.java
@@ -42,7 +42,7 @@ public DateTimeData() {
 
     }
 
-    public DateTimeData (Date d) {
+    public DateTimeData (@NotNull Date d) {
         setValue(d);
     }
 
@@ -52,7 +52,7 @@ public IAnswerData clone () {
     }
 
     @Override
-    public void setValue (Object o) {
+    public void setValue (@NotNull Object o) {
         //Should not ever be possible to set this to a null value
         if(o == null) {
             throw new NullPointerException("Attempt to set an IAnswerData class to null.");
diff --git a/src/main/java/org/javarosa/core/model/data/DecimalData.java b/src/main/java/org/javarosa/core/model/data/DecimalData.java
index 74e22bebb..412ae07e7 100644
--- a/src/main/java/org/javarosa/core/model/data/DecimalData.java
+++ b/src/main/java/org/javarosa/core/model/data/DecimalData.java
@@ -45,7 +45,7 @@ public DecimalData() {
     public DecimalData(double d) {
         this.d = d;
     }
-    public DecimalData(Double d) {
+    public DecimalData(@NotNull Double d) {
         setValue(d);
     }
 
@@ -65,7 +65,7 @@ public String getDisplayText() {
     }
 
     @Override
-    public void setValue(Object o) {
+    public void setValue(@NotNull Object o) {
         if(o == null) {
             throw new NullPointerException("Attempt to set an IAnswerData class to null.");
         }
diff --git a/src/main/java/org/javarosa/core/model/data/GeoPointData.java b/src/main/java/org/javarosa/core/model/data/GeoPointData.java
index 72ddf4ace..275d3b8ae 100644
--- a/src/main/java/org/javarosa/core/model/data/GeoPointData.java
+++ b/src/main/java/org/javarosa/core/model/data/GeoPointData.java
@@ -115,7 +115,7 @@ public String getDisplayText() {
 
 
     @Override
-    public void setValue(Object o) {
+    public void setValue(@NotNull Object o) {
         if (o == null) {
             throw new NullPointerException("Attempt to set an IAnswerData class to null.");
         }
diff --git a/src/main/java/org/javarosa/core/model/data/GeoShapeData.java b/src/main/java/org/javarosa/core/model/data/GeoShapeData.java
index d684d867b..98714be02 100644
--- a/src/main/java/org/javarosa/core/model/data/GeoShapeData.java
+++ b/src/main/java/org/javarosa/core/model/data/GeoShapeData.java
@@ -114,7 +114,7 @@ public String getDisplayText() {
     }
 
     @Override
-    public void setValue(Object o) {
+    public void setValue(@NotNull Object o) {
         if (o == null) {
             throw new NullPointerException("Attempt to set an IAnswerData class to null.");
         }
diff --git a/src/main/java/org/javarosa/core/model/data/GeoTraceData.java b/src/main/java/org/javarosa/core/model/data/GeoTraceData.java
index df66af7a2..3d7275b43 100644
--- a/src/main/java/org/javarosa/core/model/data/GeoTraceData.java
+++ b/src/main/java/org/javarosa/core/model/data/GeoTraceData.java
@@ -120,7 +120,7 @@ public String getDisplayText() {
 
 
     @Override
-    public void setValue(Object o) {
+    public void setValue(@NotNull Object o) {
         if (o == null) {
             throw new NullPointerException("Attempt to set an IAnswerData class to null.");
         }
diff --git a/src/main/java/org/javarosa/core/model/data/IAnswerData.java b/src/main/java/org/javarosa/core/model/data/IAnswerData.java
index 9399c0ced..8ebfc79b6 100644
--- a/src/main/java/org/javarosa/core/model/data/IAnswerData.java
+++ b/src/main/java/org/javarosa/core/model/data/IAnswerData.java
@@ -125,7 +125,7 @@ static IAnswerData wrapData(Object val, int intDataType) {
      * Null Data will not overwrite existing values.
      * @throws NullPointerException if o is null
      */
-    void setValue (Object o); //can't be null
+    void setValue (@NotNull Object o); //can't be null
     /**
      * @return The value of this answer, will never
      * be null
diff --git a/src/main/java/org/javarosa/core/model/data/IntegerData.java b/src/main/java/org/javarosa/core/model/data/IntegerData.java
index c5ec4ed41..f37dd35f7 100644
--- a/src/main/java/org/javarosa/core/model/data/IntegerData.java
+++ b/src/main/java/org/javarosa/core/model/data/IntegerData.java
@@ -45,7 +45,7 @@ public IntegerData() {
     public IntegerData(int n) {
         this.n = n;
     }
-    public IntegerData(Integer n) {
+    public IntegerData(@NotNull Integer n) {
         setValue(n);
     }
 
@@ -65,7 +65,7 @@ public String getDisplayText() {
     }
 
     @Override
-    public void setValue(Object o) {
+    public void setValue(@NotNull Object o) {
         if(o == null) {
             throw new NullPointerException("Attempt to set an IAnswerData class to null.");
         }
diff --git a/src/main/java/org/javarosa/core/model/data/LongData.java b/src/main/java/org/javarosa/core/model/data/LongData.java
index c6097ea23..e33289121 100644
--- a/src/main/java/org/javarosa/core/model/data/LongData.java
+++ b/src/main/java/org/javarosa/core/model/data/LongData.java
@@ -44,7 +44,7 @@ public LongData() {
     public LongData(long n) {
         this.n = n;
     }
-    public LongData(Long n) {
+    public LongData(@NotNull Long n) {
         setValue(n);
     }
 
@@ -64,7 +64,7 @@ public String getDisplayText() {
     }
 
     @Override
-    public void setValue(Object o) {
+    public void setValue(@NotNull Object o) {
         if(o == null) {
             throw new NullPointerException("Attempt to set an IAnswerData class to null.");
         }
diff --git a/src/main/java/org/javarosa/core/model/data/MultiPointerAnswerData.java b/src/main/java/org/javarosa/core/model/data/MultiPointerAnswerData.java
index c088e91a1..453a48997 100644
--- a/src/main/java/org/javarosa/core/model/data/MultiPointerAnswerData.java
+++ b/src/main/java/org/javarosa/core/model/data/MultiPointerAnswerData.java
@@ -65,7 +65,7 @@ public String getDisplayText() {
     }
 
     @Override
-    public void setValue(Object o) {
+    public void setValue(@NotNull Object o) {
         if(o == null) {
             throw new NullPointerException("Attempt to set an IAnswerData class to null.");
         }
diff --git a/src/main/java/org/javarosa/core/model/data/MultipleItemsData.java b/src/main/java/org/javarosa/core/model/data/MultipleItemsData.java
index 2c4f30404..c3be74e85 100644
--- a/src/main/java/org/javarosa/core/model/data/MultipleItemsData.java
+++ b/src/main/java/org/javarosa/core/model/data/MultipleItemsData.java
@@ -49,7 +49,7 @@ public MultipleItemsData() {
 
     }
 
-    public MultipleItemsData(List<Selection> vs) {
+    public MultipleItemsData(@NotNull List<Selection> vs) {
         setValue(vs);
     }
 
@@ -63,7 +63,7 @@ public IAnswerData clone () {
     }
 
     @Override
-    public void setValue (Object o) {
+    public void setValue (@NotNull Object o) {
         if(o == null) {
             throw new NullPointerException("Attempt to set an IAnswerData class to null.");
         }
diff --git a/src/main/java/org/javarosa/core/model/data/PointerAnswerData.java b/src/main/java/org/javarosa/core/model/data/PointerAnswerData.java
index 48755b770..29088a6dc 100644
--- a/src/main/java/org/javarosa/core/model/data/PointerAnswerData.java
+++ b/src/main/java/org/javarosa/core/model/data/PointerAnswerData.java
@@ -66,7 +66,7 @@ public String getDisplayText() {
     }
 
     @Override
-    public void setValue(Object o) {
+    public void setValue(@NotNull Object o) {
         if(o == null) {
             throw new NullPointerException("Attempt to set an IAnswerData class to null.");
         }
diff --git a/src/main/java/org/javarosa/core/model/data/SelectMultiData.java b/src/main/java/org/javarosa/core/model/data/SelectMultiData.java
index 02e86dbe8..f1bfcb6b4 100644
--- a/src/main/java/org/javarosa/core/model/data/SelectMultiData.java
+++ b/src/main/java/org/javarosa/core/model/data/SelectMultiData.java
@@ -17,6 +17,7 @@
 package org.javarosa.core.model.data;
 
 import org.javarosa.core.model.data.helper.Selection;
+import org.jetbrains.annotations.NotNull;
 
 import java.util.List;
 
@@ -32,7 +33,7 @@ public SelectMultiData() {
 
     }
 
-    public SelectMultiData(List<Selection> vs) {
+    public SelectMultiData(@NotNull List<Selection> vs) {
         setValue(vs);
     }
 }
diff --git a/src/main/java/org/javarosa/core/model/data/SelectOneData.java b/src/main/java/org/javarosa/core/model/data/SelectOneData.java
index 4b393853a..dce5536e1 100644
--- a/src/main/java/org/javarosa/core/model/data/SelectOneData.java
+++ b/src/main/java/org/javarosa/core/model/data/SelectOneData.java
@@ -45,7 +45,7 @@ public SelectOneData() {
 
     }
 
-    public SelectOneData (Selection s) {
+    public SelectOneData (@NotNull Selection s) {
         setValue(s);
     }
 
@@ -55,7 +55,7 @@ public IAnswerData clone () {
     }
 
     @Override
-    public void setValue (Object o) {
+    public void setValue (@NotNull Object o) {
         if(o == null) {
             throw new NullPointerException("Attempt to set an IAnswerData class to null.");
         }
diff --git a/src/main/java/org/javarosa/core/model/data/StringData.java b/src/main/java/org/javarosa/core/model/data/StringData.java
index eb83ed9b7..24e1d95c6 100644
--- a/src/main/java/org/javarosa/core/model/data/StringData.java
+++ b/src/main/java/org/javarosa/core/model/data/StringData.java
@@ -41,7 +41,7 @@ public StringData() {
 
     }
 
-    public StringData (String s) {
+    public StringData (@NotNull String s) {
         setValue(s);
     }
 
@@ -51,7 +51,7 @@ public IAnswerData clone () {
     }
 
     @Override
-    public void setValue (Object o) {
+    public void setValue (@NotNull Object o) {
         //string should not be null or empty; the entire StringData reference should be null in this case
         if(o == null) {
             throw new NullPointerException("Attempt to set an IAnswerData class to null.");
diff --git a/src/main/java/org/javarosa/core/model/data/TimeData.java b/src/main/java/org/javarosa/core/model/data/TimeData.java
index 8c919ad78..5a9b753b3 100644
--- a/src/main/java/org/javarosa/core/model/data/TimeData.java
+++ b/src/main/java/org/javarosa/core/model/data/TimeData.java
@@ -37,7 +37,7 @@ public class TimeData implements IAnswerData {
     public TimeData() {
     }
 
-    public TimeData (Date d) {
+    public TimeData (@NotNull Date d) {
         setValue(d);
     }
 
@@ -47,7 +47,7 @@ public IAnswerData clone () {
     }
 
     @Override
-    public void setValue (Object o) {
+    public void setValue (@NotNull Object o) {
         if(o == null) {
             throw new NullPointerException("Attempt to set an IAnswerData class to null.");
         }
diff --git a/src/main/java/org/javarosa/core/model/data/UncastData.java b/src/main/java/org/javarosa/core/model/data/UncastData.java
index c94d5be0d..e5c00f443 100644
--- a/src/main/java/org/javarosa/core/model/data/UncastData.java
+++ b/src/main/java/org/javarosa/core/model/data/UncastData.java
@@ -52,7 +52,7 @@ public String getDisplayText() {
     }
 
     @Override
-    public void setValue(Object o) {
+    public void setValue(@NotNull Object o) {
         value = (String)o;
     }