【解决方法】先将缓冲区分析BufferEnd类型设置为平头FILAT，然后再单独对左缓冲区(leftDistance)或右缓冲区(rightDistance)分别重新设置BufferDistance，需要注意BufferDistance的value值不能设置为0，参数需要>0才能正常创建缓冲区并分析。可参考以下代码：
bufferDistance1 = new SuperMap.REST.BufferDistance({
value: 250
}), //左缓冲区距离
bufferDistance2 = new SuperMap.REST.BufferDistance({
value: 0.01
}),//右缓存区距离
bufferSetting = new SuperMap.REST.BufferSetting({
endType: SuperMap.REST.BufferEndType.FLAT,
leftDistance: bufferDistance1,
rightDistance: bufferDistance2,
semicircleLineSegment: 10
}),
