Removes PlainSelect casting

Author: thmasker

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

@@ -237,7 +237,7 @@ private static String detectProjection(Statement statement) {
 		}
 
 		StringJoiner joiner = new StringJoiner(", ");
-		for (SelectItem<?> selectItem : ((PlainSelect) selectBody).getSelectItems()) {
+    	for (SelectItem<?> selectItem : selectBody.getPlainSelect().getSelectItems()) {
 			joiner.add(selectItem.toString());
 		}
 		return joiner.toString().trim();

spring-data-jpa/src/test/java/org/springframework/data/jpa/repository/query/JSqlParserQueryEnhancerUnitTests.java

@@ -257,4 +257,13 @@ static Stream<Arguments> mergeStatementWorksSource() {
 						null));
 	}
 
+	@Test // GH-3869
+	void shouldWorkWithoutFromClause() {
+		String query = "SELECT is_contained_in(:innerId, :outerId)";
+
+		StringQuery stringQuery = new StringQuery(query, true);
+
+		assertThat(stringQuery.getQueryString()).isEqualTo(query);
+	}
+
 }