get Helper Text
Returns the helper message that was set to be displayed with setHelperText(CharSequence), or null if no helper text was set or if helper text functionality is not enabled.
See also
#setHelperText(CharSequence)
Returns the helper message that was set to be displayed with setHelperText(CharSequence), or null if no helper text was set or if helper text functionality is not enabled.
#setHelperText(CharSequence)