No longer allowing putting multiple values into single-valued item.

infra/prism/src/main/java/com/evolveum/midpoint/prism/Item.java

@@ -429,8 +429,12 @@ public boolean add(@NotNull V newValue, boolean checkUniqueness) throws SchemaEx
     	if (checkUniqueness && containsEquivalentValue(newValue)) {
     		return false;
     	}
-    	if (getDefinition() != null) {
-    		newValue.applyDefinition(getDefinition(), false);
+	    D definition = getDefinition();
+	    if (definition != null) {
+		    if (!isEmpty() && definition.isSingleValue()) {
+			    throw new SchemaException("Attempt to put more than one value to single-valued item " + this + "; newly added value: " + newValue);
+		    }
+    		newValue.applyDefinition(definition, false);
     	}
     	return values.add(newValue);
     }

infra/schema/src/test/java/com/evolveum/midpoint/schema/TestMiscellaneous.java

@@ -0,0 +1,76 @@
+/*
+ * Copyright (c) 2010-2017 Evolveum
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.evolveum.midpoint.schema;
+
+import com.evolveum.midpoint.prism.Containerable;
+import com.evolveum.midpoint.prism.PrismContainer;
+import com.evolveum.midpoint.prism.PrismContainerValue;
+import com.evolveum.midpoint.prism.util.PrismTestUtil;
+import com.evolveum.midpoint.schema.constants.MidPointConstants;
+import com.evolveum.midpoint.util.PrettyPrinter;
+import com.evolveum.midpoint.util.exception.SchemaException;
+import com.evolveum.midpoint.xml.ns._public.common.common_3.AssignmentType;
+import com.evolveum.midpoint.xml.ns._public.common.common_3.ObjectReferenceType;
+import com.evolveum.midpoint.xml.ns._public.common.common_3.RoleType;
+import com.evolveum.midpoint.xml.ns._public.common.common_3.UserType;
+import org.testng.annotations.BeforeSuite;
+import org.testng.annotations.Test;
+import org.xml.sax.SAXException;
+
+import java.io.IOException;
+
+import static com.evolveum.midpoint.prism.util.PrismTestUtil.getPrismContext;
+import static org.testng.AssertJUnit.fail;
+
+/**
+ * @author mederly
+ *
+ */
+public class TestMiscellaneous {
+
+	@BeforeSuite
+	public void setup() throws SchemaException, SAXException, IOException {
+		PrettyPrinter.setDefaultNamespacePrefix(MidPointConstants.NS_MIDPOINT_PUBLIC_PREFIX);
+		PrismTestUtil.resetPrismContext(MidPointPrismContextFactory.FACTORY);
+	}
+
+	@Test
+	public void singleValuedItems() throws Exception {
+		System.out.println("===[ singleValuedItems ]===");
+
+		UserType userBean = getPrismContext().createObjectable(UserType.class)
+				.beginAssignment()
+						.id(1L)
+						.targetRef(new ObjectReferenceType().oid("123456").type(RoleType.COMPLEX_TYPE))
+				.end();
+
+		//noinspection unchecked
+		PrismContainerValue<AssignmentType> assignmentPcv = userBean.getAssignment().get(0).asPrismContainerValue();
+		PrismContainer<Containerable> limitContentPc = assignmentPcv
+				.findOrCreateContainer(AssignmentType.F_LIMIT_TARGET_CONTENT);
+		PrismContainerValue<Containerable> val1 = limitContentPc.createNewValue();
+		val1.setId(1L);
+		PrismContainerValue<Containerable> val2 = val1.clone();
+		val2.setId(2L);
+		try {
+			limitContentPc.add(val2);
+			fail("unexpected success");
+		} catch (SchemaException e) {
+			System.out.println("Got expected exception: " + e);
+		}
+	}
+
+}

infra/schema/testng-unit.xml

@@ -135,6 +135,7 @@
             <class name="com.evolveum.midpoint.schema.TestOperationResult"/>
             <class name="com.evolveum.midpoint.schema.util.SelectorOptionsTest"/>
             <class name="com.evolveum.midpoint.schema.TestEmptyItems"/>
+            <class name="com.evolveum.midpoint.schema.TestMiscellaneous"/>
         </classes>
     </test>
 </suite>