Polishing.

Rename "null handling" to "null precedence".
This is somewhat inconsistent with commons null handling, but more descriptive.

Minor formatting.

Original pull request #1156
See #821

Author: schauder

spring-data-jdbc/src/test/java/org/springframework/data/jdbc/core/JdbcAggregateTemplateIntegrationTests.java

@@ -258,8 +258,8 @@ void saveAndLoadManyEntitiesWithReferencedEntitySortedAndPaged() {
 	}
 
 	@Test // GH-821
-	@EnabledOnFeature({SUPPORTS_QUOTED_IDS, SUPPORTS_NULL_HANDLING})
-	void saveAndLoadManyEntitiesWithReferencedEntitySortedWithNullHandling() {
+	@EnabledOnFeature({SUPPORTS_QUOTED_IDS, SUPPORTS_NULL_PRECEDENCE})
+	void saveAndLoadManyEntitiesWithReferencedEntitySortedWithNullPrecedence() {
 
 		template.save(createLegoSet(null));
 		template.save(createLegoSet("Star"));

spring-data-jdbc/src/test/java/org/springframework/data/jdbc/testing/TestDatabaseFeatures.java

@@ -84,7 +84,7 @@ private void supportsMultiDimensionalArrays() {
 		assumeThat(database).isNotIn(Database.H2, Database.Hsql);
 	}
 
-	private void supportsNullHandling() {
+	private void supportsNullPrecedence() {
 		assumeThat(database).isNotIn(Database.MySql, Database.MariaDb, Database.SqlServer);
 	}
 
@@ -120,7 +120,7 @@ public enum Feature {
 		SUPPORTS_ARRAYS(TestDatabaseFeatures::supportsArrays), //
 		SUPPORTS_GENERATED_IDS_IN_REFERENCED_ENTITIES(TestDatabaseFeatures::supportsGeneratedIdsInReferencedEntities), //
 		SUPPORTS_NANOSECOND_PRECISION(TestDatabaseFeatures::supportsNanosecondPrecision), //
-		SUPPORTS_NULL_HANDLING(TestDatabaseFeatures::supportsNullHandling),
+		SUPPORTS_NULL_PRECEDENCE(TestDatabaseFeatures::supportsNullPrecedence),
 		IS_POSTGRES(f -> f.databaseIs(Database.PostgreSql)), //
 		IS_HSQL(f -> f.databaseIs(Database.Hsql));
 

spring-data-relational/src/main/java/org/springframework/data/relational/core/dialect/AbstractDialect.java

@@ -103,14 +103,14 @@ static class DialectSelectRenderContext implements SelectRenderContext {
 
 		private final Function<Select, ? extends CharSequence> afterFromTable;
 		private final Function<Select, ? extends CharSequence> afterOrderBy;
-		private final OrderByNullHandling orderByNullHandling;
+		private final OrderByNullPrecedence orderByNullPrecedence;
 
 		DialectSelectRenderContext(Function<Select, ? extends CharSequence> afterFromTable,
-				Function<Select, ? extends CharSequence> afterOrderBy, OrderByNullHandling orderByNullHandling) {
+				Function<Select, ? extends CharSequence> afterOrderBy, OrderByNullPrecedence orderByNullPrecedence) {
 
 			this.afterFromTable = afterFromTable;
 			this.afterOrderBy = afterOrderBy;
-			this.orderByNullHandling = orderByNullHandling;
+			this.orderByNullPrecedence = orderByNullPrecedence;
 		}
 
 		@Override
@@ -125,7 +125,7 @@ static class DialectSelectRenderContext implements SelectRenderContext {
 
 		@Override
 		public String evaluateOrderByNullHandling(Sort.NullHandling nullHandling) {
-			return orderByNullHandling.evaluate(nullHandling);
+			return orderByNullPrecedence.evaluate(nullHandling);
 		}
 	}
 

spring-data-relational/src/main/java/org/springframework/data/relational/core/dialect/Dialect.java

@@ -123,11 +123,12 @@ default InsertRenderContext getInsertRenderContext() {
 	}
 
 	/**
-	 * Return the {@link OrderByNullHandling} used by this dialect.
+	 * Return the {@link OrderByNullPrecedence} used by this dialect.
 	 *
-	 * @return the {@link OrderByNullHandling} used by this dialect.
+	 * @return the {@link OrderByNullPrecedence} used by this dialect.
+	 * @since 2.4
 	 */
-	default OrderByNullHandling orderByNullHandling() {
-		return OrderByNullHandling.SQL_STANDARD;
+	default OrderByNullPrecedence orderByNullHandling() {
+		return OrderByNullPrecedence.SQL_STANDARD;
 	}
 }

spring-data-relational/src/main/java/org/springframework/data/relational/core/dialect/MySqlDialect.java

@@ -135,7 +135,7 @@ public Collection<Object> getConverters() {
 	}
 
 	@Override
-	public OrderByNullHandling orderByNullHandling() {
-		return OrderByNullHandling.NONE;
+	public OrderByNullPrecedence orderByNullHandling() {
+		return OrderByNullPrecedence.NONE;
 	}
 }

spring-data-relational/src/main/java/org/springframework/data/relational/core/dialect/OrderByNullHandling.java renamed to spring-data-relational/src/main/java/org/springframework/data/relational/core/dialect/OrderByNullPrecedence.java

@@ -21,21 +21,22 @@
  * Represents how the {@link Sort.NullHandling} option of an {@code ORDER BY} sort expression is to be evaluated.
  *
  * @author Chirag Tailor
+ * @since 2.4
  */
-public interface OrderByNullHandling {
+public interface OrderByNullPrecedence {
 	/**
-	 * An {@link OrderByNullHandling} that can be used for databases conforming to the SQL standard which uses
+	 * An {@link OrderByNullPrecedence} that can be used for databases conforming to the SQL standard which uses
 	 * {@code NULLS FIRST} and {@code NULLS LAST} in {@code ORDER BY} sort expressions to make null values appear before
 	 * or after non-null values in the result set.
 	 */
-	OrderByNullHandling SQL_STANDARD = new SqlStandardOrderByNullHandling();
+	OrderByNullPrecedence SQL_STANDARD = new SqlStandardOrderByNullPrecedence();
 
 	/**
-	 * An {@link OrderByNullHandling} that can be used for databases that do not support the SQL standard usage of
+	 * An {@link OrderByNullPrecedence} that can be used for databases that do not support the SQL standard usage of
 	 * {@code NULLS FIRST} and {@code NULLS LAST} in {@code ORDER BY} sort expressions to control where null values appear
 	 * respective to non-null values in the result set.
 	 */
-	OrderByNullHandling NONE = nullHandling -> "";
+	OrderByNullPrecedence NONE = nullHandling -> "";
 
 	/**
 	 * Converts a {@link Sort.NullHandling} option to the appropriate SQL text to be included an {@code ORDER BY} sort
@@ -44,13 +45,13 @@ public interface OrderByNullHandling {
 	String evaluate(Sort.NullHandling nullHandling);
 
 	/**
-	 * An {@link OrderByNullHandling} implementation for databases conforming to the SQL standard which uses
+	 * An {@link OrderByNullPrecedence} implementation for databases conforming to the SQL standard which uses
 	 * {@code NULLS FIRST} and {@code NULLS LAST} in {@code ORDER BY} sort expressions to make null values appear before
 	 * or after non-null values in the result set.
 	 *
 	 * @author Chirag Tailor
 	 */
-	class SqlStandardOrderByNullHandling implements OrderByNullHandling {
+	class SqlStandardOrderByNullPrecedence implements OrderByNullPrecedence {
 
 		private static final String NULLS_FIRST = "NULLS FIRST";
 		private static final String NULLS_LAST = "NULLS LAST";

spring-data-relational/src/main/java/org/springframework/data/relational/core/dialect/SqlServerDialect.java

@@ -118,7 +118,7 @@ public InsertRenderContext getInsertRenderContext() {
 	}
 
 	@Override
-	public OrderByNullHandling orderByNullHandling() {
-		return OrderByNullHandling.NONE;
+	public OrderByNullPrecedence orderByNullHandling() {
+		return OrderByNullPrecedence.NONE;
 	}
 }

spring-data-relational/src/main/java/org/springframework/data/relational/core/sql/render/OrderByClauseVisitor.java

@@ -53,14 +53,16 @@ Delegation enterMatched(OrderByField segment) {
 	Delegation leaveMatched(OrderByField segment) {
 
 		if (segment.getDirection() != null) {
+
 			builder.append(" ") //
 					.append(segment.getDirection());
 		}
 
-		String nullHandling = context.getSelectRenderContext().evaluateOrderByNullHandling(segment.getNullHandling());
-		if (!nullHandling.isEmpty()) {
+		String nullPrecedence = context.getSelectRenderContext().evaluateOrderByNullHandling(segment.getNullHandling());
+		if (!nullPrecedence.isEmpty()) {
+			
 			builder.append(" ") //
-					.append(nullHandling);
+					.append(nullPrecedence);
 		}
 
 		return Delegation.leave();

spring-data-relational/src/main/java/org/springframework/data/relational/core/sql/render/SelectRenderContext.java

@@ -19,7 +19,7 @@
 import java.util.function.Function;
 
 import org.springframework.data.domain.Sort;
-import org.springframework.data.relational.core.dialect.OrderByNullHandling;
+import org.springframework.data.relational.core.dialect.OrderByNullPrecedence;
 import org.springframework.data.relational.core.sql.LockMode;
 import org.springframework.data.relational.core.sql.Select;
 
@@ -95,8 +95,9 @@ public interface SelectRenderContext {
 	 *
 	 * @param nullHandling the {@link Sort.NullHandling} for the {@code ORDER BY} sort expression. Must not be {@literal null}.
 	 * @return render {@link String} SQL text to be included in an {@code ORDER BY} sort expression.
+	 * @since 2.4
 	 */
 	default String evaluateOrderByNullHandling(Sort.NullHandling nullHandling) {
-		return OrderByNullHandling.NONE.evaluate(nullHandling);
+		return OrderByNullPrecedence.NONE.evaluate(nullHandling);
 	}
 }

spring-data-relational/src/test/java/org/springframework/data/relational/core/dialect/PostgresDialectRenderingUnitTests.java

@@ -181,7 +181,7 @@ void shouldRenderSelectOrderByWithDirection() {
 	}
 
 	@Test // GH-821
-	void shouldRenderSelectOrderByWithNullHandling() {
+	void shouldRenderSelectOrderByWithNullPrecedence() {
 
 		Table table = Table.create("foo");
 		Select select = StatementBuilder.select(table.asterisk())