[wpimath] ExponentialProfile: Return copy of input state (#6370)

As State is mutable, this avoids accidental modification of the passed-in object by the caller modifying the return value.

wpimath/src/main/java/edu/wpi/first/math/trajectory/ExponentialProfile.java

@@ -191,7 +191,7 @@ public class ExponentialProfile {
     var timing = calculateProfileTiming(current, inflectionPoint, goal, u);
 
     if (t < 0) {
-      return current;
+      return new State(current.position, current.velocity);
     } else if (t < timing.inflectionTime) {
       return new State(
           computeDistanceFromTime(t, u, current), computeVelocityFromTime(t, u, current));
@@ -200,7 +200,7 @@ public class ExponentialProfile {
           computeDistanceFromTime(t - timing.totalTime, -u, goal),
           computeVelocityFromTime(t - timing.totalTime, -u, goal));
     } else {
-      return goal;
+      return new State(goal.position, goal.velocity);
     }
   }