diff --git a/spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/convert/MongoExampleMapper.java b/spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/convert/MongoExampleMapper.java
index 8d9039441..493d0ddfd 100644
--- a/spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/convert/MongoExampleMapper.java
+++ b/spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/convert/MongoExampleMapper.java
@@ -48,16 +48,26 @@ import org.springframework.util.ObjectUtils;
 import org.springframework.util.StringUtils;
 
 /**
+ * Mapper from {@link Example} to a query {@link Document}.
+ *
  * @author Christoph Strobl
  * @author Mark Paluch
  * @author Jens Schauder
  * @since 1.8
+ * @see Example
+ * @see org.springframework.data.domain.ExampleMatcher
+ * @see UntypedExampleMatcher
  */
 public class MongoExampleMapper {
 
 	private final MappingContext<? extends MongoPersistentEntity<?>, MongoPersistentProperty> mappingContext;
 	private final MongoConverter converter;
 
+	/**
+	 * Create a new {@link MongoTypeMapper} given {@link MongoConverter}.
+	 *
+	 * @param converter must not be {@literal null}.
+	 */
 	public MongoExampleMapper(MongoConverter converter) {
 
 		this.converter = converter;
@@ -112,28 +122,63 @@ public class MongoExampleMapper {
 		return updateTypeRestrictions(result, example);
 	}
 
-	private static Document orConcatenate(Document source) {
-
-		List<Document> foo = new ArrayList<Document>(source.keySet().size());
+	private void applyPropertySpecs(String path, Document source, Class<?> probeType,
+			ExampleMatcherAccessor exampleSpecAccessor) {
 
-		for (String key : source.keySet()) {
-			foo.add(new Document(key, source.get(key)));
+		if (source == null) {
+			return;
 		}
 
-		return new Document("$or", foo);
-	}
+		Iterator<Map.Entry<String, Object>> iter = source.entrySet().iterator();
 
-	private Set<Class<?>> getTypesToMatch(Example<?> example) {
+		while (iter.hasNext()) {
 
-		Set<Class<?>> types = new HashSet<Class<?>>();
+			Map.Entry<String, Object> entry = iter.next();
+			String propertyPath = StringUtils.hasText(path) ? path + "." + entry.getKey() : entry.getKey();
+			String mappedPropertyPath = getMappedPropertyPath(propertyPath, probeType);
 
-		for (TypeInformation<?> reference : mappingContext.getManagedTypes()) {
-			if (example.getProbeType().isAssignableFrom(reference.getType())) {
-				types.add(reference.getType());
+			if (isEmptyIdProperty(entry)) {
+				iter.remove();
+				continue;
 			}
-		}
 
-		return types;
+			if (exampleSpecAccessor.isIgnoredPath(propertyPath) || exampleSpecAccessor.isIgnoredPath(mappedPropertyPath)) {
+				iter.remove();
+				continue;
+			}
+
+			StringMatcher stringMatcher = exampleSpecAccessor.getDefaultStringMatcher();
+			Object value = entry.getValue();
+			boolean ignoreCase = exampleSpecAccessor.isIgnoreCaseEnabled();
+
+			if (exampleSpecAccessor.hasPropertySpecifiers()) {
+
+				mappedPropertyPath = exampleSpecAccessor.hasPropertySpecifier(propertyPath) ? propertyPath
+						: getMappedPropertyPath(propertyPath, probeType);
+
+				stringMatcher = exampleSpecAccessor.getStringMatcherForPath(mappedPropertyPath);
+				ignoreCase = exampleSpecAccessor.isIgnoreCaseForPath(mappedPropertyPath);
+			}
+
+			// TODO: should a PropertySpecifier outrule the later on string matching?
+			if (exampleSpecAccessor.hasPropertySpecifier(mappedPropertyPath)) {
+
+				PropertyValueTransformer valueTransformer = exampleSpecAccessor.getValueTransformerForPath(mappedPropertyPath);
+				value = valueTransformer.convert(value);
+				if (value == null) {
+					iter.remove();
+					continue;
+				}
+
+				entry.setValue(value);
+			}
+
+			if (entry.getValue() instanceof String) {
+				applyStringMatcher(entry, stringMatcher, ignoreCase);
+			} else if (entry.getValue() instanceof Document) {
+				applyPropertySpecs(propertyPath, (Document) entry.getValue(), probeType, exampleSpecAccessor);
+			}
+		}
 	}
 
 	private String getMappedPropertyPath(String path, Class<?> probeType) {
@@ -142,9 +187,9 @@ public class MongoExampleMapper {
 
 		Iterator<String> parts = Arrays.asList(path.split("\\.")).iterator();
 
-		final Stack<MongoPersistentProperty> stack = new Stack<MongoPersistentProperty>();
+		final Stack<MongoPersistentProperty> stack = new Stack<>();
 
-		List<String> resultParts = new ArrayList<String>();
+		List<String> resultParts = new ArrayList<>();
 
 		while (parts.hasNext()) {
 
@@ -178,70 +223,64 @@ public class MongoExampleMapper {
 		return StringUtils.collectionToDelimitedString(resultParts, ".");
 	}
 
-	private void applyPropertySpecs(String path, Document source, Class<?> probeType,
-			ExampleMatcherAccessor exampleSpecAccessor) {
-
-		if (!(source instanceof Document)) {
-			return;
-		}
+	private Document updateTypeRestrictions(Document query, Example example) {
 
-		Iterator<Map.Entry<String, Object>> iter = ((Document) source).entrySet().iterator();
+		Document result = new Document();
 
-		while (iter.hasNext()) {
+		if (isTypeRestricting(example)) {
 
-			Map.Entry<String, Object> entry = iter.next();
-			String propertyPath = StringUtils.hasText(path) ? path + "." + entry.getKey() : entry.getKey();
-			String mappedPropertyPath = getMappedPropertyPath(propertyPath, probeType);
+			result.putAll(query);
+			this.converter.getTypeMapper().writeTypeRestrictions(result, getTypesToMatch(example));
+			return result;
+		}
 
-			if (isEmptyIdProperty(entry)) {
-				iter.remove();
-				continue;
+		for (Map.Entry<String, Object> entry : query.entrySet()) {
+			if (!this.converter.getTypeMapper().isTypeKey(entry.getKey())) {
+				result.put(entry.getKey(), entry.getValue());
 			}
+		}
 
-			if (exampleSpecAccessor.isIgnoredPath(propertyPath) || exampleSpecAccessor.isIgnoredPath(mappedPropertyPath)) {
-				iter.remove();
-				continue;
-			}
+		return result;
+	}
 
-			StringMatcher stringMatcher = exampleSpecAccessor.getDefaultStringMatcher();
-			Object value = entry.getValue();
-			boolean ignoreCase = exampleSpecAccessor.isIgnoreCaseEnabled();
+	private boolean isTypeRestricting(Example example) {
 
-			if (exampleSpecAccessor.hasPropertySpecifiers()) {
+		if (example.getMatcher() instanceof UntypedExampleMatcher) {
+			return false;
+		}
 
-				mappedPropertyPath = exampleSpecAccessor.hasPropertySpecifier(propertyPath) ? propertyPath
-						: getMappedPropertyPath(propertyPath, probeType);
+		if (example.getMatcher().getIgnoredPaths().isEmpty()) {
+			return true;
+		}
 
-				stringMatcher = exampleSpecAccessor.getStringMatcherForPath(mappedPropertyPath);
-				ignoreCase = exampleSpecAccessor.isIgnoreCaseForPath(mappedPropertyPath);
+		for (String path : example.getMatcher().getIgnoredPaths()) {
+			if (this.converter.getTypeMapper().isTypeKey(path)) {
+				return false;
 			}
+		}
 
-			// TODO: should a PropertySpecifier outrule the later on string matching?
-			if (exampleSpecAccessor.hasPropertySpecifier(mappedPropertyPath)) {
+		return true;
+	}
 
-				PropertyValueTransformer valueTransformer = exampleSpecAccessor.getValueTransformerForPath(mappedPropertyPath);
-				value = valueTransformer.convert(value);
-				if (value == null) {
-					iter.remove();
-					continue;
-				}
+	private Set<Class<?>> getTypesToMatch(Example<?> example) {
 
-				entry.setValue(value);
-			}
+		Set<Class<?>> types = new HashSet<>();
 
-			if (entry.getValue() instanceof String) {
-				applyStringMatcher(entry, stringMatcher, ignoreCase);
-			} else if (entry.getValue() instanceof Document) {
-				applyPropertySpecs(propertyPath, (Document) entry.getValue(), probeType, exampleSpecAccessor);
+		for (TypeInformation<?> reference : mappingContext.getManagedTypes()) {
+			if (example.getProbeType().isAssignableFrom(reference.getType())) {
+				types.add(reference.getType());
 			}
 		}
+
+		return types;
 	}
 
-	private boolean isEmptyIdProperty(Entry<String, Object> entry) {
+	private static boolean isEmptyIdProperty(Entry<String, Object> entry) {
 		return entry.getKey().equals("_id") && entry.getValue() == null || entry.getValue().equals(Optional.empty());
 	}
 
-	private void applyStringMatcher(Map.Entry<String, Object> entry, StringMatcher stringMatcher, boolean ignoreCase) {
+	private static void applyStringMatcher(Map.Entry<String, Object> entry, StringMatcher stringMatcher,
+			boolean ignoreCase) {
 
 		Document document = new Document();
 
@@ -264,9 +303,20 @@ public class MongoExampleMapper {
 		}
 	}
 
+	private static Document orConcatenate(Document source) {
+
+		List<Document> or = new ArrayList<>(source.keySet().size());
+
+		for (String key : source.keySet()) {
+			or.add(new Document(key, source.get(key)));
+		}
+
+		return new Document("$or", or);
+	}
+
 	/**
 	 * Return the {@link MatchMode} for the given {@link StringMatcher}.
-	 * 
+	 *
 	 * @param matcher must not be {@literal null}.
 	 * @return
 	 */
@@ -288,43 +338,4 @@ public class MongoExampleMapper {
 				return MatchMode.DEFAULT;
 		}
 	}
-
-	private Document updateTypeRestrictions(Document query, Example example) {
-
-		Document result = new Document();
-
-		if (isTypeRestricting(example)) {
-
-			result.putAll(query);
-			this.converter.getTypeMapper().writeTypeRestrictions(result, getTypesToMatch(example));
-			return result;
-		}
-
-		for (Map.Entry<String, Object> entry : query.entrySet()) {
-			if (!this.converter.getTypeMapper().isTypeKey(entry.getKey())) {
-				result.put(entry.getKey(), entry.getValue());
-			}
-		}
-
-		return result;
-	}
-
-	private boolean isTypeRestricting(Example example) {
-
-		if (example.getMatcher() instanceof UntypedExampleMatcher) {
-			return false;
-		}
-
-		if (example.getMatcher().getIgnoredPaths().isEmpty()) {
-			return true;
-		}
-
-		for (String path : example.getMatcher().getIgnoredPaths()) {
-			if (this.converter.getTypeMapper().isTypeKey(path)) {
-				return false;
-			}
-		}
-
-		return true;
-	}
 }
diff --git a/spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/query/UntypedExampleMatcher.java b/spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/query/UntypedExampleMatcher.java
index 34a031441..893fff69c 100644
--- a/spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/query/UntypedExampleMatcher.java
+++ b/spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/query/UntypedExampleMatcher.java
@@ -15,36 +15,29 @@
  */
 package org.springframework.data.mongodb.core.query;
 
+import lombok.AccessLevel;
 import lombok.EqualsAndHashCode;
+import lombok.NonNull;
+import lombok.RequiredArgsConstructor;
 
 import java.util.Set;
 
 import org.springframework.data.domain.ExampleMatcher;
-import org.springframework.util.Assert;
 
 /**
  * {@link ExampleMatcher} implementation for query by example (QBE). Unlike plain {@link ExampleMatcher} this untyped
- * counterpart does not enforce a strict type match when executing the query. This allows to use totally unrelated
- * example documents as references for querying collections as long as the used field/property names match.
+ * counterpart does not enforce type matching when executing the query. This allows to query unrelated example documents
+ * as references for querying collections as long as the used field/property names match.
  *
  * @author Christoph Strobl
+ * @author Mark Paluch
  * @since 2.0
  */
 @EqualsAndHashCode
+@RequiredArgsConstructor(access = AccessLevel.PRIVATE)
 public class UntypedExampleMatcher implements ExampleMatcher {
 
-	private final ExampleMatcher delegate;
-
-	/**
-	 * Creates new {@link UntypedExampleMatcher}.
-	 *
-	 * @param delegate must not be {@literal null}.
-	 */
-	private UntypedExampleMatcher(ExampleMatcher delegate) {
-
-		Assert.notNull(delegate, "Delegate must not be null!");
-		this.delegate = delegate;
-	}
+	private final @NonNull ExampleMatcher delegate;
 
 	/*
 	 * (non-Javadoc)
@@ -167,7 +160,7 @@ public class UntypedExampleMatcher implements ExampleMatcher {
 		return delegate.getNullHandler();
 	}
 
-	/* 
+	/*
 	 * (non-Javadoc)
 	 * @see org.springframework.data.domain.ExampleMatcher#getDefaultStringMatcher()
 	 */
@@ -175,7 +168,7 @@ public class UntypedExampleMatcher implements ExampleMatcher {
 		return delegate.getDefaultStringMatcher();
 	}
 
-	/* 
+	/*
 	 * (non-Javadoc)
 	 * @see org.springframework.data.domain.ExampleMatcher#isIgnoreCaseEnabled()
 	 */
diff --git a/spring-data-mongodb/src/test/java/org/springframework/data/mongodb/core/convert/MongoExampleMapperUnitTests.java b/spring-data-mongodb/src/test/java/org/springframework/data/mongodb/core/convert/MongoExampleMapperUnitTests.java
index 8e8ba379e..21249ab47 100644
--- a/spring-data-mongodb/src/test/java/org/springframework/data/mongodb/core/convert/MongoExampleMapperUnitTests.java
+++ b/spring-data-mongodb/src/test/java/org/springframework/data/mongodb/core/convert/MongoExampleMapperUnitTests.java
@@ -484,7 +484,7 @@ public class MongoExampleMapperUnitTests {
 	}
 
 	@Test // DATAMONGO-1768
-	public void untypedExampleShouldNotInfereTypeRestriction() {
+	public void untypedExampleShouldNotInferTypeRestriction() {
 
 		WrapperDocument probe = new WrapperDocument();
 		probe.flatDoc = new FlatDocument();