Improving Excel generation performance through calling Java

I'm still on a quest to improve our Excel document creation performance.
I've created the following java program to perform what Scott Klement's RPG
service program did, to create a text cell, but doing the 4 steps in Java
to hopefully get improved performance. I'm having problems either
specifying the java header stuff correctly, or in specifying the RPG
prototype, because I get a java.lang.NoClassDefFoundError: HSSFtext error
when calling a program using the prototype. Can anyone see where I'm going
wrong?

Java program:
import org.apache.poi.hssf.usermodel.HSSFCell;
import org.apache.poi.hssf.usermodel.HSSFCellStyle;
import org.apache.poi.hssf.usermodel.HSSFRow;
import org.apache.poi.hssf.usermodel.HSSFRichTextString;

public final class HSSFtext {
public static void main(HSSFRow Row, int Col, String value,
HSSFCellStyle style ) {

HSSFCell Cell = Row.createCell(Col);
Cell.setCellType(1);
//wwStr = new_String(peString);
Cell.setCellValue(new HSSFRichTextString(value));
Cell.setCellStyle(style);

}
}



RPG prototype:
D hssf_textz...
D PR EXTPROC(*JAVA
D :'HSSFtext'
D :'main')
D* peRow like(HSSFRow)
D peCol like(jshort) value
D peString like(jstring)
D peStyle like(HSSFCellStyle)