Remove superfluous @NonNull annotations.

Closes #2976

src/main/java/org/springframework/data/convert/PropertyValueConversionService.java

@@ -16,7 +16,6 @@
 package org.springframework.data.convert;
 
 import org.springframework.data.mapping.PersistentProperty;
-import org.springframework.lang.NonNull;
 import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
@@ -42,7 +41,7 @@ public class PropertyValueConversionService {
 	 * @throws IllegalArgumentException if {@link CustomConversions} is {@literal null}.
 	 * @see CustomConversions
 	 */
-	public PropertyValueConversionService(@NonNull CustomConversions conversions) {
+	public PropertyValueConversionService(CustomConversions conversions) {
 
 		Assert.notNull(conversions, "CustomConversions must not be null");
 

src/main/java/org/springframework/data/convert/PropertyValueConverter.java

@@ -18,7 +18,6 @@
 import java.util.function.BiFunction;
 
 import org.springframework.data.mapping.PersistentProperty;
-import org.springframework.lang.NonNull;
 import org.springframework.lang.Nullable;
 
 /**
@@ -48,8 +47,8 @@ public interface PropertyValueConverter<DV, SV, C extends ValueConversionContext
 	 * operation.
 	 *
 	 * @param value value to read.
-	 * @param context {@link ValueConversionContext} containing store-specific metadata
-	 * used in the value conversion; never {@literal null}.
+	 * @param context {@link ValueConversionContext} containing store-specific metadata used in the value conversion;
+	 *          never {@literal null}.
 	 * @return the converted value. Can be {@literal null}.
 	 */
 	@Nullable
@@ -59,8 +58,8 @@ public interface PropertyValueConverter<DV, SV, C extends ValueConversionContext
 	 * Convert the given {@code null} value from the store into its domain value representation. Typically, a
 	 * {@literal read} operation. Returns {@code null} by default.
 	 *
-	 * @param context {@link ValueConversionContext} containing store-specific metadata
-	 * used in the value conversion; never {@literal null}.
+	 * @param context {@link ValueConversionContext} containing store-specific metadata used in the value conversion;
+	 *          never {@literal null}.
 	 * @return the converted value. Can be {@literal null}.
 	 */
 	@Nullable
@@ -73,8 +72,8 @@ default DV readNull(C context) {
 	 * operation.
 	 *
 	 * @param value value to write; can be {@literal null}.
-	 * @param context {@link ValueConversionContext} containing store-specific metadata
-	 * used in the value conversion; never {@literal null}.
+	 * @param context {@link ValueConversionContext} containing store-specific metadata used in the value conversion;
+	 *          never {@literal null}.
 	 * @return the converted value. Can be {@literal null}.
 	 */
 	@Nullable
@@ -84,8 +83,8 @@ default DV readNull(C context) {
 	 * Convert the given {@code null} value from the domain model into it's native store representation. Typically, a
 	 * {@literal write} operation. Returns {@code null} by default.
 	 *
-	 * @param context {@link ValueConversionContext} containing store-specific metadata
-	 * used in the value conversion; never {@literal null}.
+	 * @param context {@link ValueConversionContext} containing store-specific metadata used in the value conversion;
+	 *          never {@literal null}.
 	 * @return the converted value. Can be {@literal null}.
 	 */
 	@Nullable
@@ -127,32 +126,32 @@ class FunctionPropertyValueConverter<DV, SV, P extends PersistentProperty<P>>
 		private final BiFunction<DV, ValueConversionContext<P>, SV> writer;
 		private final BiFunction<SV, ValueConversionContext<P>, DV> reader;
 
-		public FunctionPropertyValueConverter(@NonNull BiFunction<DV, ValueConversionContext<P>, SV> writer,
-				@NonNull BiFunction<SV, ValueConversionContext<P>, DV> reader) {
+		public FunctionPropertyValueConverter(BiFunction<DV, ValueConversionContext<P>, SV> writer,
+				BiFunction<SV, ValueConversionContext<P>, DV> reader) {
 
 			this.writer = writer;
 			this.reader = reader;
 		}
 
 		@Nullable
 		@Override
-		public SV write(@Nullable DV value, @NonNull ValueConversionContext<P> context) {
+		public SV write(@Nullable DV value, ValueConversionContext<P> context) {
 			return writer.apply(value, context);
 		}
 
 		@Override
-		public SV writeNull(@NonNull ValueConversionContext<P> context) {
+		public SV writeNull(ValueConversionContext<P> context) {
 			return writer.apply(null, context);
 		}
 
 		@Nullable
 		@Override
-		public DV read(@Nullable SV value, @NonNull ValueConversionContext<P> context) {
+		public DV read(@Nullable SV value, ValueConversionContext<P> context) {
 			return reader.apply(value, context);
 		}
 
 		@Override
-		public DV readNull(@NonNull ValueConversionContext<P> context) {
+		public DV readNull(ValueConversionContext<P> context) {
 			return reader.apply(null, context);
 		}
 	}

src/main/java/org/springframework/data/convert/PropertyValueConverterFactories.java

@@ -215,10 +215,12 @@ static class Cache {
 			Map<PersistentProperty<?>, Optional<PropertyValueConverter<?, ?, ? extends ValueConversionContext<?>>>> perPropertyCache = new ConcurrentHashMap<>();
 			Map<Class<?>, Optional<PropertyValueConverter<?, ?, ? extends ValueConversionContext<?>>>> typeCache = new ConcurrentHashMap<>();
 
+			@Nullable
 			Optional<PropertyValueConverter<?, ?, ? extends ValueConversionContext<?>>> get(PersistentProperty<?> property) {
 				return perPropertyCache.get(property);
 			}
 
+			@Nullable
 			Optional<PropertyValueConverter<?, ?, ? extends ValueConversionContext<?>>> get(Class<?> type) {
 				return typeCache.get(type);
 			}

src/main/java/org/springframework/data/convert/PropertyValueConverterRegistrar.java

@@ -22,7 +22,6 @@
 import org.springframework.data.convert.PropertyValueConverter.FunctionPropertyValueConverter;
 import org.springframework.data.mapping.PersistentProperty;
 import org.springframework.data.util.MethodInvocationRecorder;
-import org.springframework.lang.NonNull;
 import org.springframework.util.Assert;
 
 /**
@@ -106,7 +105,7 @@ public PropertyValueConverterRegistrar<P> registerConverter(Class<?> type, Strin
 	 * @throws IllegalArgumentException if the {@link ValueConverterRegistry} is {@literal null}.
 	 * @see ValueConverterRegistry
 	 */
-	public void registerConvertersIn(@NonNull ValueConverterRegistry<P> target) {
+	public void registerConvertersIn(ValueConverterRegistry<P> target) {
 
 		Assert.notNull(target, "Target registry must not be null");
 
@@ -119,7 +118,7 @@ public void registerConvertersIn(@NonNull ValueConverterRegistry<P> target) {
 	 *
 	 * @return new instance of {@link SimplePropertyValueConverterRegistry}.
 	 */
-	@NonNull
+
 	public ValueConverterRegistry<P> buildRegistry() {
 		return new SimplePropertyValueConverterRegistry<>(registry);
 	}
@@ -135,7 +134,7 @@ public static class WritingConverterRegistrationBuilder<T, S, P extends Persiste
 		private final PropertyValueConverterRegistrar<P> config;
 
 		WritingConverterRegistrationBuilder(Class<T> type, String property,
-				@NonNull PropertyValueConverterRegistrar<P> config) {
+				PropertyValueConverterRegistrar<P> config) {
 
 			this.config = config;
 			this.registration = converter -> config.registerConverter(type, property, converter);
@@ -173,8 +172,8 @@ public static class ReadingConverterRegistrationBuilder<T, S, R, P extends Persi
 		private final WritingConverterRegistrationBuilder<T, S, P> origin;
 		private final BiFunction<S, ValueConversionContext<P>, R> writer;
 
-		ReadingConverterRegistrationBuilder(@NonNull WritingConverterRegistrationBuilder<T, S, P> origin,
-				@NonNull BiFunction<S, ValueConversionContext<P>, R> writer) {
+		ReadingConverterRegistrationBuilder(WritingConverterRegistrationBuilder<T, S, P> origin,
+				BiFunction<S, ValueConversionContext<P>, R> writer) {
 
 			this.origin = origin;
 			this.writer = writer;

src/main/java/org/springframework/data/convert/SimplePropertyValueConversions.java

@@ -22,7 +22,6 @@
 import org.springframework.beans.factory.InitializingBean;
 import org.springframework.data.convert.PropertyValueConverterFactories.ChainedPropertyValueConverterFactory;
 import org.springframework.data.mapping.PersistentProperty;
-import org.springframework.lang.NonNull;
 import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
@@ -44,8 +43,7 @@
  */
 public class SimplePropertyValueConversions implements PropertyValueConversions, InitializingBean {
 
-	private static final String NO_CONVERTER_FACTORY_ERROR_MESSAGE =
-			"PropertyValueConverterFactory is not set; Make sure to either set the converter factory or call afterPropertiesSet() to initialize the object";
+	private static final String NO_CONVERTER_FACTORY_ERROR_MESSAGE = "PropertyValueConverterFactory is not set; Make sure to either set the converter factory or call afterPropertiesSet() to initialize the object";
 
 	private boolean converterCacheEnabled = true;
 
@@ -57,7 +55,7 @@ public class SimplePropertyValueConversions implements PropertyValueConversions,
 	 * Set the {@link PropertyValueConverterFactory} responsible for creating the actual {@link PropertyValueConverter}.
 	 *
 	 * @param converterFactory {@link PropertyValueConverterFactory} used to create the actual
-	 * {@link PropertyValueConverter}.
+	 *          {@link PropertyValueConverter}.
 	 * @see PropertyValueConverterFactory
 	 */
 	public void setConverterFactory(@Nullable PropertyValueConverterFactory converterFactory) {
@@ -76,7 +74,7 @@ public PropertyValueConverterFactory getConverterFactory() {
 		return converterFactory;
 	}
 
-	private @NonNull PropertyValueConverterFactory requireConverterFactory() {
+	private PropertyValueConverterFactory requireConverterFactory() {
 
 		PropertyValueConverterFactory factory = getConverterFactory();
 
@@ -113,28 +111,27 @@ public ValueConverterRegistry<?> getValueConverterRegistry() {
 	/**
 	 * Configure whether to use converter the cache. Enabled by default.
 	 *
-	 * @param converterCacheEnabled set to {@literal true} to enable caching of
-	 * {@link PropertyValueConverter converter} instances.
+	 * @param converterCacheEnabled set to {@literal true} to enable caching of {@link PropertyValueConverter converter}
+	 *          instances.
 	 */
 	public void setConverterCacheEnabled(boolean converterCacheEnabled) {
 		this.converterCacheEnabled = converterCacheEnabled;
 	}
 
 	/**
-	 * Determines whether a {@link PropertyValueConverter} has been registered for
-	 * the given {@link PersistentProperty property}.
+	 * Determines whether a {@link PropertyValueConverter} has been registered for the given {@link PersistentProperty
+	 * property}.
 	 *
 	 * @param property {@link PersistentProperty} to evaluate.
-	 * @return {@literal true} if a {@link PropertyValueConverter} has been registered for
-	 * the given {@link PersistentProperty property}.
+	 * @return {@literal true} if a {@link PropertyValueConverter} has been registered for the given
+	 *         {@link PersistentProperty property}.
 	 * @see PersistentProperty
 	 */
 	@Override
 	public boolean hasValueConverter(PersistentProperty<?> property) {
 		return requireConverterFactory().getConverter(property) != null;
 	}
 
-	@NonNull
 	@Override
 	public <DV, SV, P extends PersistentProperty<P>, D extends ValueConversionContext<P>> PropertyValueConverter<DV, SV, D> getValueConverter(
 			P property) {
@@ -155,8 +152,7 @@ public void init() {
 
 		factoryList.add(resolveConverterFactory());
 
-		resolveConverterRegistryAsConverterFactory()
-				.ifPresent(factoryList::add);
+		resolveConverterRegistryAsConverterFactory().ifPresent(factoryList::add);
 
 		PropertyValueConverterFactory targetFactory = factoryList.size() > 1
 				? PropertyValueConverterFactory.chained(factoryList)
@@ -166,18 +162,16 @@ public void init() {
 				: targetFactory;
 	}
 
-	private @NonNull PropertyValueConverterFactory resolveConverterFactory() {
+	private PropertyValueConverterFactory resolveConverterFactory() {
 
 		PropertyValueConverterFactory converterFactory = getConverterFactory();
 
-		return converterFactory != null ? converterFactory
-				: PropertyValueConverterFactory.simple();
+		return converterFactory != null ? converterFactory : PropertyValueConverterFactory.simple();
 	}
 
 	private Optional<PropertyValueConverterFactory> resolveConverterRegistryAsConverterFactory() {
 
-		return Optional.ofNullable(getValueConverterRegistry())
-				.filter(it -> !it.isEmpty())
+		return Optional.ofNullable(getValueConverterRegistry()).filter(it -> !it.isEmpty())
 				.map(PropertyValueConverterFactory::configuredInstance);
 	}
 

src/main/java/org/springframework/data/convert/ValueConversionContext.java

@@ -17,7 +17,6 @@
 
 import org.springframework.data.mapping.PersistentProperty;
 import org.springframework.data.util.TypeInformation;
-import org.springframework.lang.NonNull;
 import org.springframework.lang.Nullable;
 
 /**
@@ -47,7 +46,7 @@ public interface ValueConversionContext<P extends PersistentProperty<P>> {
 	 * @param value {@link Object value} to write; can be {@literal null}.
 	 * @return can be {@literal null}.
 	 * @throws IllegalStateException if value cannot be written as an instance of the
-	 * {@link PersistentProperty#getTypeInformation() property type}.
+	 *           {@link PersistentProperty#getTypeInformation() property type}.
 	 * @see PersistentProperty#getTypeInformation()
 	 * @see #write(Object, TypeInformation)
 	 */
@@ -67,7 +66,7 @@ default Object write(@Nullable Object value) {
 	 * @see TypeInformation
 	 */
 	@Nullable
-	default <T> T write(@Nullable Object value, @NonNull Class<T> target) {
+	default <T> T write(@Nullable Object value, Class<T> target) {
 		return write(value, TypeInformation.of(target));
 	}
 
@@ -81,7 +80,7 @@ default <T> T write(@Nullable Object value, @NonNull Class<T> target) {
 	 * @see TypeInformation
 	 */
 	@Nullable
-	default <T> T write(@Nullable Object value, @NonNull TypeInformation<T> target) {
+	default <T> T write(@Nullable Object value, TypeInformation<T> target) {
 
 		if (value == null || target.getType().isInstance(value)) {
 			return target.getType().cast(value);
@@ -97,7 +96,7 @@ default <T> T write(@Nullable Object value, @NonNull TypeInformation<T> target)
 	 * @param value {@link Object value} to be read; can be {@literal null}.
 	 * @return can be {@literal null}.
 	 * @throws IllegalStateException if value cannot be read as an instance of the
-	 * {@link PersistentProperty#getTypeInformation() property type}.
+	 *           {@link PersistentProperty#getTypeInformation() property type}.
 	 * @see PersistentProperty#getTypeInformation()
 	 * @see #read(Object, TypeInformation)
 	 */
@@ -117,7 +116,7 @@ default Object read(@Nullable Object value) {
 	 * @see TypeInformation
 	 */
 	@Nullable
-	default <T> T read(@Nullable Object value, @NonNull Class<T> target) {
+	default <T> T read(@Nullable Object value, Class<T> target) {
 		return read(value, TypeInformation.of(target));
 	}
 
@@ -131,7 +130,7 @@ default <T> T read(@Nullable Object value, @NonNull Class<T> target) {
 	 * @see TypeInformation
 	 */
 	@Nullable
-	default <T> T read(@Nullable Object value, @NonNull TypeInformation<T> target) {
+	default <T> T read(@Nullable Object value, TypeInformation<T> target) {
 
 		if (value == null || target.getType().isInstance(value)) {
 			return target.getType().cast(value);

src/main/java/org/springframework/data/repository/util/ClassUtils.java

@@ -20,7 +20,6 @@
 import java.util.Arrays;
 import java.util.Collection;
 import java.util.List;
-import java.util.Set;
 import java.util.function.Consumer;
 
 import org.springframework.data.repository.Repository;
@@ -110,7 +109,7 @@ public static boolean isGenericRepositoryInterface(@Nullable String interfaceNam
 	 * @deprecated Use {@link #getNumberOfOccurrences(Method, Class)}.
 	 */
 	@Deprecated
-	public static int getNumberOfOccurences(@NonNull Method method, @NonNull Class<?> type) {
+	public static int getNumberOfOccurences(Method method, Class<?> type) {
 		return getNumberOfOccurrences(method, type);
 	}