Program: 86659
Project: 86659
Buggy source:
public static Emitter newBulletTracerEmitter(Vector2f pos,int emitterTimeToLive){
  int maxParticles=68;
  final Emitter emitter=new Emitter(pos,emitterTimeToLive,maxParticles).setName("String_Node_Str").setDieInstantly(false);
  BatchedParticleGenerator gen=new BatchedParticleGenerator(0,maxParticles).addSingleParticleGenerator(new RandomColorSingleParticleGenerator(new Color(0xffff00ff))).addSingleParticleGenerator(new SingleParticleGenerator(){
    @Override public void onGenerateParticle(    int index,    TimeStep timeStep,    ParticleData particles){
      particles.color[index].a=0.0f;
    }
  }
).addSingleParticleGenerator(new SetPositionSingleParticleGenerator());
  emitter.addParticleGenerator(gen);
  emitter.addParticleUpdater(new ParticleUpdater(){
    @Override public void update(    TimeStep timeStep,    ParticleData particles){
      ClientEntity ent=emitter.attachedTo();
      if (ent != null) {
        for (int index=0; index < particles.numberOfAliveParticles; index++) {
          Vector2f pos=ent.getCenterPos();
          Vector2f vel=ent.getMovementDir();
          float offset=index;
          Vector2f.Vector2fMS(pos,vel,offset,particles.pos[index]);
          float percentange=(float)index / particles.numberOfAliveParticles;
          particles.color[index].a=0.9512f * (1f - percentange);
        }
      }
 else {
        for (int index=0; index < particles.numberOfAliveParticles; index++) {
          particles.color[index].a=0f;
        }
      }
    }
  }
);
  emitter.addParticleUpdater(new KillIfAttachedIsDeadUpdater());
  emitter.addParticleRenderer(new RectParticleRenderer(2,2));
  return emitter;
}

Fixed version (ground truth):
public static Emitter newBulletTracerEmitter(Vector2f pos,int emitterTimeToLive){
  int maxParticles=68;
  final Emitter emitter=new Emitter(pos,emitterTimeToLive,maxParticles).setName("String_Node_Str").setDieInstantly(false);
  BatchedParticleGenerator gen=new BatchedParticleGenerator(0,maxParticles).addSingleParticleGenerator(new RandomColorSingleParticleGenerator(new Color(0xffbA00ff),new Color(0xffff00ff))).addSingleParticleGenerator(new SingleParticleGenerator(){
    @Override public void onGenerateParticle(    int index,    TimeStep timeStep,    ParticleData particles){
      particles.color[index].a=0.0f;
    }
  }
).addSingleParticleGenerator(new SetPositionSingleParticleGenerator());
  emitter.addParticleGenerator(gen);
  emitter.addParticleUpdater(new ParticleUpdater(){
    @Override public void update(    TimeStep timeStep,    ParticleData particles){
      ClientEntity ent=emitter.attachedTo();
      if (ent != null) {
        Vector2f pos=ent.getCenterPos();
        Vector2f vel=ent.getMovementDir();
        for (int index=0; index < particles.numberOfAliveParticles; index++) {
          float offset=index;
          Vector2f.Vector2fMS(pos,vel,offset,particles.pos[index]);
          float percentange=(float)index / particles.numberOfAliveParticles;
          particles.color[index].a=0.9512f * (1f - percentange);
        }
      }
 else {
        for (int index=0; index < particles.numberOfAliveParticles; index++) {
          particles.color[index].a=0f;
        }
      }
    }
  }
);
  emitter.addParticleUpdater(new KillIfAttachedIsDeadUpdater());
  emitter.addParticleRenderer(new RectParticleRenderer(2,2));
  return emitter;
}