Add these files to Engine\Content\Editor\Templates to have file templates in Jetbrains Rider

MassStateTreeTask.cpp.template

%COPYRIGHT_LINE%

%PCH_INCLUDE_DIRECTIVE%
%MY_HEADER_INCLUDE_DIRECTIVE%
%ADDITIONAL_INCLUDE_DIRECTIVES%
#include "MassStateTreeExecutionContext.h"
#include "StateTreeLinker.h"


void %PREFIXED_CLASS_NAME%::Link(FStateTreeLinker& Linker)
{
	Linker.LinkExternalData(MassSignalSubsystemHandle);
	Linker.LinkInstanceProperty(MyVectorHandle, STATETREE_INSTANCEDATA_PROPERTY(F$UNPREFIXED_CLASS_NAME$InstanceData, MyVector));
}

void %PREFIXED_CLASS_NAME%::EnterState(FStateTreeExecutionContext& Context,
                                                       const EStateTreeStateChangeType ChangeType, const FStateTreeTransitionResult& Transition) const
{
	const FMassStateTreeExecutionContext& MassContext = static_cast<FMassStateTreeExecutionContext&>(Context);
	FVector& MyVector = Context.GetInstanceData(MyVectorHandle);
	
	// If desired, trigger a tick
	// UMassSignalSubsystem& MassSignalSubsystem = Context.GetExternalData(MassSignalSubsystemHandle);
	// MassSignalSubsystem.DelaySignalEntity(UE::Mass::Signals::StandTaskFinished, MassContext.GetEntity(), Duration);

	return EStateTreeRunStatus::Running;
}

void %PREFIXED_CLASS_NAME%::ExitState(FStateTreeExecutionContext& Context, const EStateTreeStateChangeType ChangeType,
	const FStateTreeTransitionResult& Transition) const
{
}

EStateTreeRunStatus %PREFIXED_CLASS_NAME%::Tick(FStateTreeExecutionContext& Context, const float DeltaTime) const
{
	const FMassStateTreeExecutionContext& MassContext = static_cast<FMassStateTreeExecutionContext&>(Context);
	const FMassEntityHandle Entity = MassContext.GetEntity();
	FVector& MyVector = Context.GetInstanceData(MyVectorHandle);

	// If desired, trigger a tick
	// UMassSignalSubsystem& MassSignalSubsystem = Context.GetExternalData(MassSignalSubsystemHandle);
	// MassSignalSubsystem.DelaySignalEntity(UE::Mass::Signals::StandTaskFinished, MassContext.GetEntity(), Duration);

	return EStateTreeRunStatus::Running;
}

%ADDITIONAL_MEMBER_DEFINITIONS%

MassStateTreeTask.h.template

$COPYRIGHT_LINE$

#pragma once

#include "CoreMinimal.h"
#include "MassStateTreeTypes.h"
#include "$UNPREFIXED_CLASS_NAME$.generated.h"

USTRUCT()
struct $CLASS_MODULE_API_MACRO$ F$UNPREFIXED_CLASS_NAME$InstanceData
{
	GENERATED_BODY()

  UPROPERTY()
  FVector MyVector = FVector::ZeroVector;
};


UCLASS(meta=(DisplayName = "$UNPREFIXED_CLASS_NAME$") )
class $CLASS_MODULE_API_MACRO$$PREFIX$$UNPREFIXED_CLASS_NAME$ : public UMassProcessor
{
	GENERATED_BODY()

protected:
	virtual bool Link(FStateTreeLinker& Linker) override;
	virtual const UStruct* GetInstanceDataType() const override { return FMassVehicleLoiterInstanceData::StaticStruct(); }
	virtual EStateTreeRunStatus EnterState(FStateTreeExecutionContext& Context, const EStateTreeStateChangeType ChangeType, const FStateTreeTransitionResult& Transition) const override;
	virtual void ExitState(FStateTreeExecutionContext& Context, const EStateTreeStateChangeType ChangeType, const FStateTreeTransitionResult& Transition) const override;
	virtual EStateTreeRunStatus Tick(FStateTreeExecutionContext& Context, const float DeltaTime) const override;

	TStateTreeExternalDataHandle<UMassSignalSubsystem> MassSignalSubsystemHandle;
	TStateTreeInstanceDataPropertyHandle<FVector> MyVectorHandle;
};