This jar is POI 3.8 with a fix regarding management of dates with T format (like 2012-12-13T10:23:45).

Modified class: org/apache/poi/ss/usermodel/DateUtil.java

(line 415)
for (int i = 0; i < fs.length(); i++) {
	char c = fs.charAt(i);
    if (i < fs.length() - 1) {
        char nc = fs.charAt(i + 1);
        if (c == '\\') {
            switch (nc) {
                case '-':
                case ',':
                case '.':
                case ' ':
                case '\\':
                    // skip current '\' and continue to the next char
                    continue;
+				case 'T':
+                    i++;
+                    continue;
            }
        } else if (c == ';' && nc == '@') {
            i++;
            // skip ";@" duplets
            continue;
        }
    }
	sb.append(c);
}


Modified by jjzhou 2012-11-27 for https://jira.talendforge.org/browse/TDI-23783 :
change poi-ooxml-3.8-20120326.jar file name to poi-ooxml-3.8-20121127_modified_talend.jar
class: org.apache.poi.xssf.eventusermodel.XSSFSheetXMLHandler.java
(line 26)
+import org.apache.poi.ss.usermodel.DateUtil;
(line 365)
-   thisStr = formatter.formatRawCellContents(Double.parseDouble(n), this.formatIndex, this.formatString);
+   if(!DateUtil.isADateFormat(formatIndex,formatString)) {
        java.text.DecimalFormat df = new java.text.DecimalFormat("#.####################################");
        thisStr = df.format(Double.parseDouble(n));
    }else{
        thisStr = formatter.formatRawCellContents(Double.parseDouble(n), this.formatIndex, this.formatString);
    }
    
class: org.apache.poi.xssf.extractor.TestXSSFEventBasedExcelExtractor.class
-    assertEquals(expectedOutput, fixture.getText().replace(",", "."));