Improved consistency in writing Util classes and removed raw types to make types more stable

spring-data-jpa/src/main/java/org/springframework/data/jpa/repository/query/JSqlParserUtils.java

@@ -31,9 +31,11 @@
  * @author Greg Turnquist
  * @since 2.7.0
  */
-public final class JSqlParserUtils {
+public abstract class JSqlParserUtils {
 
-	private JSqlParserUtils() {}
+	private JSqlParserUtils() {
+		throw new IllegalStateException("Cannot instantiate a utility class!");
+	}
 
 	/**
 	 * Generates a count function call, based on the {@code countFields}.
@@ -49,7 +51,7 @@ public static Function getJSqlCount(final List<String> countFields, final boolea
 				.map(Column::new) //
 				.collect(Collectors.toList());
 
-		ExpressionList countExpression = new ExpressionList(countColumns);
+		ExpressionList<Expression> countExpression = new ExpressionList<>(countColumns);
 
 		return new Function() //
 				.withName("count") //
@@ -66,7 +68,7 @@ public static Function getJSqlCount(final List<String> countFields, final boolea
 	public static Function getJSqlLower(String column) {
 
 		List<Expression> expressions = Collections.singletonList(new Column(column));
-		ExpressionList lowerParamExpression = new ExpressionList(expressions);
+		ExpressionList<Expression> lowerParamExpression = new ExpressionList<>(expressions);
 
 		return new Function() //
 				.withName("lower") //

spring-data-jpa/src/main/java/org/springframework/data/jpa/repository/query/Meta.java

@@ -43,7 +43,7 @@ private enum MetaKey {
 		}
 	}
 
-	private Map<String, Object> values = Collections.emptyMap();
+	private Map<String, Object> values = new LinkedHashMap<>(2);
 
 	public Meta() {}
 
@@ -100,10 +100,6 @@ void setValue(String key, @Nullable Object value) {
 
 		Assert.hasText(key, "Meta key must not be 'null' or blank");
 
-		if (values == Collections.EMPTY_MAP) {
-			values = new LinkedHashMap<>(2);
-		}
-
 		if (value == null || (value instanceof String stringValue && !StringUtils.hasText(stringValue))) {
 			this.values.remove(key);
 		}

spring-data-jpa/src/main/java/org/springframework/data/jpa/repository/query/NamedQuery.java

@@ -107,9 +107,8 @@ static boolean hasNamedQuery(EntityManager em, String queryName) {
 		 * See DATAJPA-617, we have to use a dedicated em for the lookups to avoid a
 		 * potential rollback of the running tx.
 		 */
-		EntityManager lookupEm = em.getEntityManagerFactory().createEntityManager();
 
-		try {
+		try (EntityManager lookupEm = em.getEntityManagerFactory().createEntityManager()) {
 			lookupEm.createNamedQuery(queryName);
 			return true;
 		} catch (IllegalArgumentException e) {
@@ -118,8 +117,6 @@ static boolean hasNamedQuery(EntityManager em, String queryName) {
 				LOG.debug(String.format("Did not find named query %s", queryName));
 			}
 			return false;
-		} finally {
-			lookupEm.close();
 		}
 	}
 

spring-data-jpa/src/main/java/org/springframework/data/jpa/support/PageableUtils.java

@@ -24,7 +24,7 @@
  * @author Greg Turnquist
  * @since 3.0
  */
-public final class PageableUtils {
+public abstract class PageableUtils {
 
 	private PageableUtils() {
 		throw new IllegalStateException("Cannot instantiate a utility class!");