I have code that call Oracle funqtion:

public Map<String, Object> canRefuse(int val) {
    SimpleJdbcCall simpleJdbcCall = new SimpleJdbcCall(jdbcTemplate)
            .withSchemaName("custom")
            .withCatalogName("pkg")
            .withFunctionName("foo");

    SqlParameterSource parameterSource = new MapSqlParameterSource()
            .addValue("val", val);

    return simpleJdbcCall.execute(parameterSource);
}

but It throws exception:

org.springframework.jdbc.BadSqlGrammarException: CallableStatementCallback; bad SQL grammar [{? = call custom.pkg.foo(?)}] ...
Caused by: oracle.jdbc.OracleDatabaseException: ORA-06503: PL/SQL: Function returned without value ORA-06512: at "custom.pkg", line 1207 ORA-06512: at line 1

I could not find any way to overcome this problem