Adjusted nullness annotations to conform to expected return values.

databind/src/main/java/gov/nist/secauto/metaschema/databind/SimpleModuleLoaderStrategy.java

@@ -16,7 +16,9 @@ public class SimpleModuleLoaderStrategy
   @NonNull
   private static final IModuleBindingGenerator COMPILATION_DISABLED_GENERATOR = module -> {
     throw new UnsupportedOperationException(
-        "Dynamic compilation of Metaschema modules is not enabled by default. Configure a different IModuleBindingGenerator with the IModuleLoaderStrategy used with the IBindignContext.");
+        "Dynamic compilation of Metaschema modules is not enabled by default." +
+            " Configure a different IModuleBindingGenerator with the IModuleLoaderStrategy" +
+            " used with the IBindignContext.");
   };
 
   @NonNull

databind/src/main/java/gov/nist/secauto/metaschema/databind/io/json/MetaschemaJsonReader.java

@@ -163,7 +163,13 @@ protected ObjectMapper getObjectMapper() {
   @SuppressWarnings("unchecked")
   @NonNull
   public <T> T readObject(@NonNull IBoundDefinitionModelComplex definition) throws IOException {
-    return (T) definition.readItem(null, this);
+    T value = (T) definition.readItem(null, this);
+    if (value == null) {
+      throw new IOException(String.format("Failed to read object '%s'%s.",
+          definition.getDefinitionQName(),
+          JsonUtil.generateLocationMessage(getReader())));
+    }
+    return value;
   }
 
   @SuppressWarnings({ "unchecked" })
@@ -225,7 +231,7 @@ public <T> T readObjectRoot(
   // Instance readers
   // ================
 
-  @NonNull
+  @Nullable
   private Object readInstance(
       @NonNull IBoundProperty<?> instance,
       @NonNull IBoundObject parent) throws IOException {
@@ -319,14 +325,14 @@ public Object readItemFieldValue(IBoundObject parentItem, IBoundFieldValue field
     return checkMissingFieldValue(readScalarItem(fieldValue));
   }
 
-  @NonNull
+  @Nullable
   private Object checkMissingFieldValue(Object value) throws IOException {
     if (value == null && LOGGER.isWarnEnabled()) {
       LOGGER.atWarn().log("Missing property value{}",
           JsonUtil.generateLocationMessage(getReader()));
     }
     // TODO: change nullness annotations to be @Nullable
-    return ObjectUtils.notNull(value);
+    return value;
   }
 
   @Override
@@ -391,7 +397,9 @@ private IBoundObject readFieldObject(
           (def, parent, problem) -> {
             IBoundFieldValue fieldValue = definition.getFieldValue();
             Object item = readItemFieldValue(parent, fieldValue);
-            fieldValue.setValue(parent, item);
+            if (item != null) {
+              fieldValue.setValue(parent, item);
+            }
           },
           actualProblemHandler);
 
@@ -690,10 +698,10 @@ public boolean handleUnknownProperty(
         JsonUtil.assertAndAdvance(parser, JsonToken.FIELD_NAME);
 
         IBoundFieldValue fieldValue = ((IBoundDefinitionModelFieldComplex) definition).getFieldValue();
-        Object value = readItemFieldValue(
-            ObjectUtils.notNull(parentItem),
-            fieldValue);
-        fieldValue.setValue(ObjectUtils.notNull(parentItem), value);
+        Object value = readItemFieldValue(ObjectUtils.notNull(parentItem), fieldValue);
+        if (value != null) {
+          fieldValue.setValue(ObjectUtils.notNull(parentItem), value);
+        }
 
         retval = foundJsonValueKey = true;
       }
@@ -758,7 +766,12 @@ public Map<String, ITEM> readMap() throws IOException {
         // a map item will always start with a FIELD_NAME, since this represents the key
         JsonUtil.assertCurrent(parser, JsonToken.FIELD_NAME);
 
+        // get the object, since it must have a JSON key
         ITEM item = readItem();
+        if (item == null) {
+          throw new IOException(String.format("Null object encountered'%s.",
+              JsonUtil.generateLocationMessage(parser)));
+        }
 
         // lookup the key
         IBoundInstanceFlag jsonKey = instance.getItemJsonKey(item);
@@ -785,7 +798,6 @@ public Map<String, ITEM> readMap() throws IOException {
     }
 
     @Override
-    @NonNull
     public ITEM readItem() throws IOException {
       IBoundInstanceModel<ITEM> instance = getCollectionInfo().getInstance();
       return instance.readItem(getParentObject(), MetaschemaJsonReader.this);

databind/src/main/java/gov/nist/secauto/metaschema/databind/io/xml/MetaschemaXmlReader.java

@@ -144,7 +144,13 @@ public <CLASS> CLASS read(@NonNull IBoundDefinitionModelComplex definition) thro
       }
 
       ItemReadHandler handler = new ItemReadHandler(ObjectUtils.notNull(event.asStartElement()));
-      return ObjectUtils.asType(definition.readItem(null, handler));
+      Object value = definition.readItem(null, handler);
+      if (value == null) {
+        throw new IOException(String.format("Unable to read data%s",
+            XmlEventUtil.generateLocationMessage(reader.peek())));
+      }
+
+      return ObjectUtils.asType(value);
     } catch (XMLStreamException ex) {
       throw new IOException(ex);
     }
@@ -476,7 +482,9 @@ private void handleFieldDefinitionBody(
 
       // parse the value
       Object value = fieldValue.readItem(item, this);
-      fieldValue.setValue(item, value);
+      if (value != null) {
+        fieldValue.setValue(item, value);
+      }
     }
 
     @Override
@@ -494,7 +502,7 @@ public Object readItemField(
           XmlEventUtil.requireStartElement(getReader(), wrapper);
         }
 
-        Object retval = checkMissingFieldValue(readScalarItem(instance));
+        Object retval = readScalarItem(instance);
 
         if (wrapper != null) {
           XmlEventUtil.skipWhitespace(getReader());
@@ -550,15 +558,13 @@ public Object readItemFieldValue(
       return checkMissingFieldValue(readScalarItem(fieldValue));
     }
 
-    @SuppressWarnings("null")
-    @NonNull
+    @Nullable
     private Object checkMissingFieldValue(Object value) throws IOException {
       if (value == null && LOGGER.isWarnEnabled()) {
         StartElement start = getStartElement();
         LOGGER.atWarn().log("Missing property value{}",
             XmlEventUtil.generateLocationMessage(start));
       }
-      // TODO: change nullness annotations to be @Nullable
       return value;
     }
 

databind/src/main/java/gov/nist/secauto/metaschema/databind/model/info/IItemReadHandler.java

@@ -50,7 +50,7 @@ Object readItemFlag(
    * @throws IOException
    *           if an error occurred while parsing
    */
-  @NonNull
+  @Nullable
   Object readItemField(
       @NonNull IBoundObject parent,
       @NonNull IBoundInstanceModelFieldScalar instance) throws IOException;
@@ -115,7 +115,7 @@ IBoundObject readItemField(
    * @throws IOException
    *           if an error occurred while parsing
    */
-  @NonNull
+  @Nullable
   Object readItemFieldValue(
       @NonNull IBoundObject parent,
       @NonNull IBoundFieldValue fieldValue) throws IOException;
@@ -180,7 +180,7 @@ IBoundObject readItemAssembly(
    * @throws IOException
    *           if an error occurred while parsing
    */
-  @NonNull
+  @Nullable
   IBoundObject readChoiceGroupItem(
       @NonNull IBoundObject parent,
       @NonNull IBoundInstanceModelChoiceGroup instance) throws IOException;

databind/src/main/java/gov/nist/secauto/metaschema/databind/model/info/IItemValueHandler.java

@@ -33,7 +33,7 @@ public interface IItemValueHandler<TYPE> {
    * @throws IOException
    *           if an error occurred while parsing
    */
-  @NonNull
+  @Nullable
   TYPE readItem(
       @Nullable IBoundObject parent,
       @NonNull IItemReadHandler handler) throws IOException;

databind/src/main/java/gov/nist/secauto/metaschema/databind/model/info/IModelInstanceReadHandler.java

@@ -32,6 +32,7 @@ default ITEM readSingleton() throws IOException {
    * @throws IOException
    *           if an error occurred while parsing the input
    */
+  @Nullable
   ITEM readItem() throws IOException;
 
   @Nullable

databind/src/test/java/gov/nist/secauto/metaschema/databind/io/Issue206MetaschemaReaderTest.java

@@ -42,6 +42,8 @@
 import javax.xml.stream.XMLInputFactory;
 import javax.xml.stream.XMLStreamException;
 
+import edu.umd.cs.findbugs.annotations.NonNull;
+
 class Issue206MetaschemaReaderTest {
   @RegisterExtension
   JUnit5Mockery context = new JUnit5Mockery();
@@ -60,6 +62,7 @@ void testIssue205Json() throws IOException {
 
     try (InputStream is = new ByteArrayInputStream(json.getBytes(StandardCharsets.UTF_8))) {
       try (JsonParser parser = JsonFactoryFactory.instance().createParser(is)) {
+        assert parser != null;
         MetaschemaJsonReader reader = new MetaschemaJsonReader(parser);
 
         // assertThrows(IOException.class, () -> {
@@ -83,7 +86,7 @@ void testIssue205XmlNoValue() throws IOException, XMLStreamException {
 
     XMLInputFactory factory = XMLInputFactory.newInstance();
     try (InputStream is = new ByteArrayInputStream(xml.getBytes(StandardCharsets.UTF_8))) {
-      XMLEventReader2 eventReader = (XMLEventReader2) factory.createXMLEventReader(is);
+      XMLEventReader2 eventReader = ObjectUtils.notNull((XMLEventReader2) factory.createXMLEventReader(is));
       MetaschemaXmlReader reader = new MetaschemaXmlReader(eventReader);
 
       // assertThrows(IOException.class, () -> {
@@ -106,7 +109,7 @@ void testIssue205XmlEmptyValue() throws IOException, XMLStreamException {
 
     XMLInputFactory factory = XMLInputFactory.newInstance();
     try (InputStream is = new ByteArrayInputStream(xml.getBytes(StandardCharsets.UTF_8))) {
-      XMLEventReader2 eventReader = (XMLEventReader2) factory.createXMLEventReader(is);
+      XMLEventReader2 eventReader = ObjectUtils.requireNonNull((XMLEventReader2) factory.createXMLEventReader(is));
       MetaschemaXmlReader reader = new MetaschemaXmlReader(eventReader);
 
       TestField field = (TestField) reader.read(definition);
@@ -117,8 +120,12 @@ void testIssue205XmlEmptyValue() throws IOException, XMLStreamException {
   @MetaschemaModule(fields = { TestField.class })
   public static class TestModule
       extends AbstractBoundModule {
+    @NonNull
+    private static final URI NAMESPACE = ObjectUtils.notNull(URI.create("http://example.com/"));
 
-    public TestModule(List<? extends IBoundModule> importedModules, IBindingContext bindingContext) {
+    public TestModule(
+        @NonNull List<? extends IBoundModule> importedModules,
+        @NonNull IBindingContext bindingContext) {
       super(importedModules, bindingContext);
     }
 
@@ -144,17 +151,18 @@ public String getShortName() {
 
     @Override
     public URI getXmlNamespace() {
-      return URI.create("http://example.com/");
+      return NAMESPACE;
     }
 
     @Override
     public URI getJsonBaseUri() {
-      return URI.create("http://example.com/");
+      return NAMESPACE;
     }
   }
 
   @MetaschemaField(name = "test-field", moduleClass = TestModule.class)
   public static class TestField implements IBoundObject {
+    @SuppressWarnings("unused")
     public TestField(IMetaschemaData data) {
       // do nothing
     }

databind/src/test/java/gov/nist/secauto/metaschema/databind/model/DefaultFieldPropertyTest.java

@@ -85,7 +85,7 @@ void testJsonReadField()
       MetaschemaJsonReader parser = new MetaschemaJsonReader(jsonParser);
 
       // read the top-level definition
-      MultiFieldAssembly obj = (MultiFieldAssembly) parser.readObject(classBinding);
+      MultiFieldAssembly obj = ObjectUtils.requireNonNull((MultiFieldAssembly) parser.readObject(classBinding));
 
       assertAll(
           () -> assertEquals("field1value", obj.getField1()),
@@ -118,7 +118,7 @@ void testJsonReadMissingFieldValue()
       MetaschemaJsonReader parser = new MetaschemaJsonReader(jsonParser);
 
       // read the top-level definition
-      MultiFieldAssembly obj = (MultiFieldAssembly) parser.readObject(classBinding);
+      MultiFieldAssembly obj = ObjectUtils.requireNonNull((MultiFieldAssembly) parser.readObject(classBinding));
 
       assertAll(
           () -> assertNull(obj.getField1()),
@@ -144,7 +144,7 @@ void testJsonReadFieldValueKey()
       MetaschemaJsonReader parser = new MetaschemaJsonReader(jsonParser);
 
       // read the top-level definition
-      MultiFieldAssembly obj = (MultiFieldAssembly) parser.readObject(classBinding);
+      MultiFieldAssembly obj = ObjectUtils.requireNonNull((MultiFieldAssembly) parser.readObject(classBinding));
 
       assertAll(
           () -> assertEquals("theValue", obj.getField3().getValue()));
@@ -168,7 +168,7 @@ void testJsonReadFieldDefaultValueKey()
       MetaschemaJsonReader parser = new MetaschemaJsonReader(jsonParser);
 
       // read the top-level definition
-      MultiFieldAssembly obj = (MultiFieldAssembly) parser.readObject(classBinding);
+      MultiFieldAssembly obj = ObjectUtils.requireNonNull((MultiFieldAssembly) parser.readObject(classBinding));
 
       assertAll(
           () -> assertEquals("theValue", obj.getField4().getValue()));