public CaptionRectangle withLeftOffset(Double leftOffset) {
        setLeftOffset(leftOffset);
        return this;
    }
Applies only if you plan to convert these source captions to EBU-TT-D or TTML in an output. (Make sure to leave
the default if you don't have either of these formats in the output.) You can define a display rectangle for the
captions that is smaller than the underlying video frame. You define the rectangle by specifying the position of
the left edge, top edge, bottom edge, and right edge of the rectangle, all within the underlying video frame. The
units for the measurements are percentages. If you specify a value for one of these fields, you must specify a
value for all of them. For leftOffset, specify the position of the left edge of the rectangle, as a percentage of
the underlying frame width, and relative to the left edge of the frame. For example, \"10\" means the measurement
is 10% of the underlying frame width. The rectangle left edge starts at that position from the left edge of the
frame. This field corresponds to tts:origin - X in the TTML standard.

@param leftOffset
       Applies only if you plan to convert these source captions to EBU-TT-D or TTML in an output. (Make sure to
       leave the default if you don't have either of these formats in the output.) You can define a display
       rectangle for the captions that is smaller than the underlying video frame. You define the rectangle by
       specifying the position of the left edge, top edge, bottom edge, and right edge of the rectangle, all
       within the underlying video frame. The units for the measurements are percentages. If you specify a value
       for one of these fields, you must specify a value for all of them. For leftOffset, specify the position of
       the left edge of the rectangle, as a percentage of the underlying frame width, and relative to the left
       edge of the frame. For example, \"10\" means the measurement is 10% of the underlying frame width. The
       rectangle left edge starts at that position from the left edge of the frame. This field corresponds to
       tts:origin - X in the TTML standard.
@return Returns a reference to this object so that method calls can be chained together.
aws-java-sdk-medialive/src/main/java/com/amazonaws/services/medialive/model/CaptionRectangle.java