code: public void setField(Object instance, String fieldname, boolean isStatic, Object newValue)
  			throws IllegalAccessException {
  		FieldReaderWriter fieldReaderWriter = locateField(fieldname);
  		if (isStatic && !fieldReaderWriter.isStatic()) {
  			throw new IncompatibleClassChangeError("Expected static field "
  					+ fieldReaderWriter.theField.getDeclaringTypeName()
  					+ "." + fieldReaderWriter.theField.getName());
  		}
  		else if (!isStatic && fieldReaderWriter.isStatic()) {
  			throw new IncompatibleClassChangeError("Expected non-static field "
  					+ fieldReaderWriter.theField.getDeclaringTypeName()
  					+ "." + fieldReaderWriter.theField.getName());
  		}
  
  		if (fieldReaderWriter.isStatic()) {
  			fieldReaderWriter.setStaticFieldValue(getClazz(), newValue, null);
  		}
  		else {
  			fieldReaderWriter.setValue(instance, newValue, null);
  		}
  	}
docs: Attempt to set the value of a field on an instance to the specified value.
  
  @param instance the object upon which to set the field (maybe null for static fields)
  @param fieldname the name of the field
  @param isStatic whether the field is static
  @param newValue the new value to put into the field
  @throws IllegalAccessException if there is a problem setting the field value