nbOpacity top-level property Null safety

Implementation

NBOpacity nbOpacity = NBOpacity(
  dp0: 0,
  dp5: 0.05,
  dp10: 0.1,
  dp20: 0.2,
  dp25: 0.25,
  dp30: 0.3,
  dp40: 0.4,
  dp50: 0.5,
  dp60: 0.6,
  dp70: 0.7,
  dp75: 0.75,
  dp80: 0.8,
  dp90: 0.9,
  dp95: 0.95,
  dp100: 1,
);