DATACMNS-867 - Additional Java 8 language feature cleanup.

Make use of lambdas and method references though out the codebase. Remove no longer required generic type parameters.
Additionally remove unused imports and replace single element list initialization with dedicated singletonList.
Use Assertion overloads taking Supplier for dynamic assertion error messages.

src/test/java/org/springframework/data/domain/ExampleMatcherUnitTests.java

@@ -21,11 +21,6 @@ import static org.springframework.data.domain.ExampleMatcher.*;
 
 import org.junit.Before;
 import org.junit.Test;
-import org.springframework.data.domain.ExampleMatcher.GenericPropertyMatcher;
-import org.springframework.data.domain.ExampleMatcher.GenericPropertyMatchers;
-import org.springframework.data.domain.ExampleMatcher.MatcherConfigurer;
-import org.springframework.data.domain.ExampleMatcher.NullHandler;
-import org.springframework.data.domain.ExampleMatcher.StringMatcher;
 
 /**
  * Unit test for {@link ExampleMatcher}.
@@ -169,24 +164,14 @@ public class ExampleMatcherUnitTests {
 				.withNullHandler(NullHandler.IGNORE) //
 				.withIgnoreCase("ignored-case") //
 				.withMatcher("hello", GenericPropertyMatchers.contains().caseSensitive()) //
-				.withMatcher("world", new MatcherConfigurer<GenericPropertyMatcher>() {
-					@Override
-					public void configureMatcher(GenericPropertyMatcher matcher) {
-						matcher.endsWith();
-					}
-				});
+				.withMatcher("world", matcher -> matcher.endsWith());
 
 		ExampleMatcher sameAsMatcher = matching() //
 				.withIgnorePaths("foo", "bar", "baz") //
 				.withNullHandler(NullHandler.IGNORE) //
 				.withIgnoreCase("ignored-case") //
 				.withMatcher("hello", GenericPropertyMatchers.contains().caseSensitive()) //
-				.withMatcher("world", new MatcherConfigurer<GenericPropertyMatcher>() {
-					@Override
-					public void configureMatcher(GenericPropertyMatcher matcher) {
-						matcher.endsWith();
-					}
-				});
+				.withMatcher("world", matcher -> matcher.endsWith());
 
 		ExampleMatcher different = matching() //
 				.withIgnorePaths("foo", "bar", "baz") //

src/test/java/org/springframework/data/domain/ExampleUnitTests.java

@@ -20,7 +20,6 @@ import static org.springframework.data.domain.ExampleMatcher.*;
 
 import org.junit.Before;
 import org.junit.Test;
-import org.springframework.data.domain.ExampleMatcher.GenericPropertyMatchers;
 
 /**
  * Test for {@link Example}.

src/test/java/org/springframework/data/domain/PageImplUnitTests.java

@@ -34,17 +34,17 @@ public class PageImplUnitTests {
 	@Test
 	public void assertEqualsForSimpleSetup() throws Exception {
 
-		PageImpl<String> page = new PageImpl<>(Arrays.asList("Foo"));
+		PageImpl<String> page = new PageImpl<>(Collections.singletonList("Foo"));
 
 		assertEqualsAndHashcode(page, page);
-		assertEqualsAndHashcode(page, new PageImpl<>(Arrays.asList("Foo")));
+		assertEqualsAndHashcode(page, new PageImpl<>(Collections.singletonList("Foo")));
 	}
 
 	@Test
 	public void assertEqualsForComplexSetup() throws Exception {
 
 		Pageable pageable = PageRequest.of(0, 10);
-		List<String> content = Arrays.asList("Foo");
+		List<String> content = Collections.singletonList("Foo");
 
 		PageImpl<String> page = new PageImpl<>(content, pageable, 100);
 
@@ -68,7 +68,7 @@ public class PageImplUnitTests {
 	@Test
 	public void returnsNextPageable() {
 
-		Page<Object> page = new PageImpl<>(Arrays.asList(new Object()), PageRequest.of(0, 1), 10);
+		Page<Object> page = new PageImpl<>(Collections.singletonList(new Object()), PageRequest.of(0, 1), 10);
 
 		assertThat(page.isFirst()).isTrue();
 		assertThat(page.hasPrevious()).isFalse();
@@ -82,7 +82,7 @@ public class PageImplUnitTests {
 	@Test
 	public void returnsPreviousPageable() {
 
-		Page<Object> page = new PageImpl<>(Arrays.asList(new Object()), PageRequest.of(1, 1), 2);
+		Page<Object> page = new PageImpl<>(Collections.singletonList(new Object()), PageRequest.of(1, 1), 2);
 
 		assertThat(page.isFirst()).isFalse();
 		assertThat(page.hasPrevious()).isTrue();
@@ -116,7 +116,7 @@ public class PageImplUnitTests {
 	@Test // DATACMNS-323
 	public void returnsCorrectTotalPages() {
 
-		Page<String> page = new PageImpl<>(Arrays.asList("a"));
+		Page<String> page = new PageImpl<>(Collections.singletonList("a"));
 
 		assertThat(page.getTotalPages()).isEqualTo(1);
 		assertThat(page.hasNext()).isFalse();
@@ -127,7 +127,7 @@ public class PageImplUnitTests {
 	public void transformsPageCorrectly() {
 
 		Page<Integer> transformed = new PageImpl<>(Arrays.asList("foo", "bar"), PageRequest.of(0, 2), 10)
-				.map(source -> source.length());
+				.map(String::length);
 
 		assertThat(transformed.getContent()).hasSize(2);
 		assertThat(transformed.getContent()).contains(3, 3);

src/test/java/org/springframework/data/domain/jaxb/SpringDataJaxbUnitTests.java

@@ -20,6 +20,7 @@ import static org.assertj.core.api.Assertions.*;
 import java.io.IOException;
 import java.io.StringWriter;
 import java.util.Arrays;
+import java.util.Collections;
 import java.util.List;
 import java.util.Scanner;
 
@@ -103,8 +104,8 @@ public class SpringDataJaxbUnitTests {
 		PageWrapper wrapper = new PageWrapper();
 		Content content = new Content();
 		content.name = "Foo";
-		wrapper.page = new PageImpl<>(Arrays.asList(content));
-		wrapper.pageWithLinks = new PageImpl<>(Arrays.asList(content));
+		wrapper.page = new PageImpl<>(Collections.singletonList(content));
+		wrapper.pageWithLinks = new PageImpl<>(Collections.singletonList(content));
 
 		marshaller.marshal(wrapper, new StringWriter());
 	}