ORA-29531:没有方法%s(在类%s中)调用oracle PLSQL中的java源

我在PLSQL中的代码如下:

    CREATE OR REPLACE AND RESOLVE JAVA SOURCE NAMED "ConversorSQL" AS
  package test;
  import java.util.Calendar;
  import java.sql.Connection;
  import java.sql.DriverManager;
  import java.sql.ResultSet;
  import java.sql.SQLException;
  import java.sql.Statement;

  import java.io.FileReader;
  import java.io.IOException;

  public class ConversorSQL {  
    public static String runConversor(String tipoOperacion, String nombreTabla, String queryOpcional) {
      return "Hola";
    }
  }

然后:

CREATE OR REPLACE FUNCTION f_conversorSQL(p_tipo VARCHAR2,
                                      p_tabla VARCHAR2,
                                      p_query VARCHAR2) RETURN VARCHAR2 IS LANGUAGE JAVA NAME 'test.ConversorSQL.runConversor(String, String, String) return String';

  SELECT f_conversorSQL( 'Hello there!',
                       'General Kenobi',
                       'You are a bold one')
 FROM DUAL;

我得到了标题中的错误:

Error que empieza en la línea 1 del comando:
SELECT f_conversorSQL( 'Hello there!',
                       'General Kenobi',
                       'You are a bold one')
FROM DUAL;
Informe de error -
Error SQL: ORA-29531: ningún método runConversor en la clase ConversorSQL
29531. 00000 - "no method %s in class %s"
*Cause: An attempt was made to execute a non_existent method in a Java class.
*Action: Adjust the call or créate the specified method.

CREATE OR REPLACE AND RESOLVE JAVA SOURCE NAMED "JavaDate" AS
  package pruebas;
  import java.util.Calendar;
  import java.sql.Connection;
  import java.sql.DriverManager;
  import java.sql.ResultSet;
  import java.sql.SQLException;
  import java.sql.Statement;

  import java.io.FileReader;
  import java.io.IOException;

  public class JavaDate {  
    public static String getString(int anho, int mes, int dia, int hora, int minuto, int segundo) {
      return "hola";
    }
  }

同上:

    CREATE OR REPLACE FUNCTION f_javadate(p_anho NUMBER,
                                      p_mes NUMBER,
                                      p_dia NUMBER,
                                      p_hora NUMBER,
                                      p_minuto NUMBER,
                                      p_segundo NUMBER) RETURN VARCHAR2 IS LANGUAGE JAVA
 NAME 'pruebas.JavaDate.getString(int, int, int, int, int, int) return String';

SELECT f_javadate(TO_NUMBER(TO_CHAR(SYSDATE, 'YYYY')),
                  TO_NUMBER(TO_CHAR(SYSDATE, 'MM')),
                  TO_NUMBER(TO_CHAR(SYSDATE, 'DD')),
                  TO_NUMBER(TO_CHAR(SYSDATE, 'HH24')),
                  TO_NUMBER(TO_CHAR(SYSDATE, 'MI')),
                  TO_NUMBER(TO_CHAR(SYSDATE, 'SS')))
 FROM DUAL;

它们看起来几乎一样,我只更改了包名、函数名和参数数。