[docs] Add missing JavaDocs (#6146)

wpilibNewCommands/src/main/native/include/frc2/command/Command.h

@@ -426,6 +426,7 @@ class Command : public wpi::Sendable, public wpi::SendableHelper<Command> {
  protected:
   Command();
 
+  /// Requirements set.
   wpi::SmallSet<Subsystem*, 4> m_requirements;
 
   /**

wpilibNewCommands/src/main/native/include/frc2/command/PIDCommand.h

@@ -74,9 +74,16 @@ class PIDCommand : public CommandHelper<Command, PIDCommand> {
   frc::PIDController& GetController();
 
  protected:
+  /// PID controller.
   frc::PIDController m_controller;
+
+  /// Measurement getter.
   std::function<double()> m_measurement;
+
+  /// Setpoint getter.
   std::function<double()> m_setpoint;
+
+  /// PID controller output consumer.
   std::function<void(double)> m_useOutput;
 };
 }  // namespace frc2

wpilibNewCommands/src/main/native/include/frc2/command/PIDSubsystem.h

@@ -69,7 +69,10 @@ class PIDSubsystem : public SubsystemBase {
   frc::PIDController& GetController();
 
  protected:
+  /// PID controller.
   frc::PIDController m_controller;
+
+  /// Whether PID controller output is enabled.
   bool m_enabled{false};
 
   /**

wpilibNewCommands/src/main/native/include/frc2/command/ProfiledPIDCommand.h

@@ -139,9 +139,16 @@ class ProfiledPIDCommand
   frc::ProfiledPIDController<Distance>& GetController() { return m_controller; }
 
  protected:
+  /// Profiled PID controller.
   frc::ProfiledPIDController<Distance> m_controller;
+
+  /// Measurement getter.
   std::function<Distance_t()> m_measurement;
+
+  /// Goal getter.
   std::function<State()> m_goal;
+
+  /// Profiled PID controller output consumer.
   std::function<void(double, State)> m_useOutput;
 };
 }  // namespace frc2

wpilibNewCommands/src/main/native/include/frc2/command/ProfiledPIDSubsystem.h

@@ -91,7 +91,10 @@ class ProfiledPIDSubsystem : public SubsystemBase {
   frc::ProfiledPIDController<Distance>& GetController() { return m_controller; }
 
  protected:
+  /// Profiled PID controller.
   frc::ProfiledPIDController<Distance> m_controller;
+
+  /// Whether the profiled PID controller output is enabled.
   bool m_enabled{false};
 
   /**

wpilibNewCommands/src/main/native/include/frc2/command/WaitCommand.h

@@ -41,6 +41,7 @@ class WaitCommand : public CommandHelper<Command, WaitCommand> {
   void InitSendable(wpi::SendableBuilder& builder) override;
 
  protected:
+  /// The timer used for waiting.
   frc::Timer m_timer;
 
  private: