Fix parsing of single-character string literals in JPQL and EQL collection member expressions.

Signed-off-by: jewoodev <jewoos15@naver.com>

Closes #4278
Original pull request: #4282

Author: jewoodev

spring-data-jpa/src/main/antlr4/org/springframework/data/jpa/repository/query/Eql.g4

@@ -1,5 +1,5 @@
 /*
- * Copyright 2023 the original author or authors.
+ * Copyright 2023-present the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -23,6 +23,7 @@ grammar Eql;
  * @see https://eclipse.dev/eclipselink/documentation/3.0/jpa/extensions/jpql.htm
  * @author Greg Turnquist
  * @author Christoph Strobl
+ * @author Jewoo Shin
  * @since 3.2
  */
 }
@@ -677,6 +678,7 @@ constructor_name
 
 literal
     : STRINGLITERAL
+    | CHARACTER
     | JAVASTRINGLITERAL
     | INTLITERAL
     | FLOATLITERAL

spring-data-jpa/src/main/antlr4/org/springframework/data/jpa/repository/query/Jpql.g4

@@ -1,5 +1,5 @@
 /*
- * Copyright 2011-2023 the original author or authors.
+ * Copyright 2011-present the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -24,6 +24,7 @@ grammar Jpql;
  * @see https://github.com/jakartaee/persistence/blob/master/spec/src/main/asciidoc/ch04-query-language.adoc#bnf
  * @author Greg Turnquist
  * @author Christoph Strobl
+ * @author Jewoo Shin
  * @since 3.1
  */
 }
@@ -670,6 +671,7 @@ constructor_name
 
 literal
     : STRINGLITERAL
+    | CHARACTER
     | JAVASTRINGLITERAL
     | INTLITERAL
     | FLOATLITERAL

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

@@ -250,6 +250,22 @@ void specialOperators() {
 		assertQuery("SELECT p FROM Phone p WHERE FUNCTION('TO_NUMBER', p.areaCode) > 613");
 	}
 
+	@Test // GH-4278
+	void singleCharacterLiteralAsCollectionMemberExpression() {
+
+		assertQuery("SELECT e FROM Employee e WHERE 'c' MEMBER OF e.responsibilities");
+		assertQuery("SELECT e FROM Employee e WHERE 'c' NOT MEMBER OF e.responsibilities");
+
+		assertQuery("""
+				SELECT e
+				FROM Employee e
+				WHERE EXISTS (SELECT p FROM Person p WHERE 'c' MEMBER OF p.nicknames)
+				""");
+
+		assertQuery("UPDATE Employee e SET e.name = 'x' WHERE 'c' MEMBER OF e.responsibilities");
+		assertQuery("DELETE FROM Employee e WHERE 'c' MEMBER OF e.responsibilities");
+	}
+
 	@Test // GH-3314
 	void isNullAndIsNotNull() {