org.jcp.xml.dsig.internal.dom.Utils.parseIdFromSameDocumentURI throws StringIndexOutOfBoundsException when calling substring method

ADDITIONAL SYSTEM INFORMATION :
Linux, jdk 8

A DESCRIPTION OF THE PROBLEM :
For the method org.jcp.xml.dsig.internal.dom.Utils.parseIdFromSameDocumentURI,
the unit test we generated in the attached snapshot.

Maybe you would think the input parameter is invalid, but we should consider all possible situations and deal all possible exceptions.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
This is the test case we generate
@Test
  public void test_parseIdFromSameDocumentURI{
      java.lang.String string0 = "0xpointer(id(=G6^Wr*m81i?Ah{^PCS(@r8-/(bwu9;InjsXk882M&lb%)`f"; org.jcp.xml.dsig.internal.dom.Utils.parseIdFromSameDocumentURI(string0);
  }

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
do not throw StringIndexOutOfBoundsException
ACTUAL -
throw StringIndexOutOfBoundsException

---------- BEGIN SOURCE ----------
public static String parseIdFromSameDocumentURI(String uri) {
        if (uri.length() == 0) {
            return null;
        }
        String id = uri.substring(1);
        if (id.startsWith("xpointer(id(")) {
            int i1 = id.indexOf('\'');
            int i2 = id.indexOf('\'', i1+1);
            id = id.substring(i1+1, i2);
        }
        return id;
    }
---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
public static String parseIdFromSameDocumentURI(String uri) {
        if (uri.length() == 0) {
            return null;
        }
        String id = uri.substring(1);
        if (id.startsWith("xpointer(id(")) {
            int i1 = id.indexOf('\'');
            int i2 = id.indexOf('\'', i1+1);
            if (i1 + 1 >= 0 && i2 <= id.length() && i2 - i1 - 1 >= 0) {
                id = id.substring(i1+1, i2);
            }
        }
        return id;
    }

FREQUENCY : occasionally