Problem with making a floating gripper in Gazebo

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Hi, I am trying to make a floating gripper for gazebo that will be used for reinforced learning, so far I want it to move up and down and close its claws. Currently I have a problem with spawning it in gazebo simulation, because I think the urdf is not parsed correctly, because the gravity is turned off only for the first link. The code for gripper is attached below. I guess I kinda messed up with the dummy links, but I can't find any example like that.

<?xml version="1.0" ?>
<!-- =================================================================================== -->
<!-- |    Gripper file used for openai gym            | -->
<!-- |                                                | -->
<!-- =================================================================================== -->

 <robot name="Gripper">

   <gazebo reference="dummy_prismatic_link">
    <gravity>0</gravity>
    <mu1>0.5</mu1>
    <mu2>0.5</mu2>
    <material>Gazebo/Orange</material>
  </gazebo>

  <gazebo reference="dummy">
    <gravity>0</gravity>
    <mu1>0.5</mu1>
    <mu2>0.5</mu2>
    <material>Gazebo/Orange</material>
  </gazebo>

  <gazebo reference="gripper_main_body">
    <gravity>0</gravity>
    <mu1>0.5</mu1>
    <mu2>0.5</mu2>
    <material>Gazebo/Orange</material>
  </gazebo>
  <gazebo reference="gripper_finger1">
    <gravity>0</gravity>
    <mu1>0.5</mu1>
    <mu2>0.5</mu2>
    <material>Gazebo/Red</material>
  </gazebo>
  <gazebo reference="gripper_finger2">
    <gravity>0</gravity>
    <mu1>0.5</mu1>
    <mu2>0.5</mu2>
    <material>Gazebo/Red</material>
  </gazebo>

  <link name="world"/>

  <joint name="fixed" type="fixed">
    <parent link="world"/>
    <child link="dummy"/>
  </joint>

  <joint name="gripper_dummy" type="fixed">
    <parent link="dummy"/>
    <child link="dummy_prismatic_link"/>
    <origin rpy="0  0  0" xyz="0   0   0.5"/>
  </joint>

  <joint name="dummy_prismatic_joint" type="prismatic">
    <parent link="dummy_prismatic_link"/>
    <child link="gripper_main_body"/>
    <origin rpy="0  3.14159265  0" xyz="0   0   0"/>
    <axis xyz="0  0  1"/>
    <limit effort="1.0" lower="-0.0" upper="0.02" velocity="1.0"/>
    <dynamics damping="0.2"/>
  </joint>
  <transmission name="gripper_tran">
    <type>transmission_interface/SimpleTransmission</type>
    <joint name="gripper_joint">
      <hardwareInterface>EffortJointInterface</hardwareInterface>
    </joint>
    <actuator name="gripper_motor">
      <hardwareInterface>EffortJointInterface</hardwareInterface>
      <mechanicalReduction>1</mechanicalReduction>
    </actuator>
  </transmission>

  <joint name="gripper_joint1" type="prismatic">
    <parent link="gripper_main_body"/>
    <child link="gripper_finger1"/>
    <origin rpy="0  0  0" xyz="0.001   0.01375   0.12925"/>
    <axis xyz="0  1  0"/>
    <limit effort="1.0" lower="-0.01" upper="0.01" velocity="1.0"/>
    <dynamics damping="0.2"/>
  </joint>
  <transmission name="gripper_tran1">
    <type>transmission_interface/SimpleTransmission</type>
    <joint name="gripper_joint1">
      <hardwareInterface>EffortJointInterface</hardwareInterface>
    </joint>
    <actuator name="gripper_motor0">
      <hardwareInterface>EffortJointInterface</hardwareInterface>
      <mechanicalReduction>1</mechanicalReduction>
    </actuator>
  </transmission>

  <joint name="gripper_joint2" type="prismatic">
    <parent link="gripper_main_body"/>
    <child link="gripper_finger2"/>
    <origin rpy="0  0  3.14159265" xyz="0.001   -0.012   0.12925"/>
    <axis xyz="0  1  0"/>
    <limit effort="1.0" lower="-0.01" upper="0.01" velocity="1.0"/>
    <dynamics damping="0.2"/>
  </joint>
  <transmission name="gripper_tran2">
    <type>transmission_interface/SimpleTransmission</type>
    <joint name="gripper_joint2">
      <hardwareInterface>EffortJointInterface</hardwareInterface>
    </joint>
    <actuator name="gripper_motor2">
      <hardwareInterface>EffortJointInterface</hardwareInterface>
      <mechanicalReduction>1</mechanicalReduction>
    </actuator>
  </transmission>

  <link name="dummy">
    <collision name="dummy_collision">
      <origin rpy="0  0  0" xyz="0    0    0.5"/>
      <geometry>
        <cylinder length="0.014" radius="0.003"/>
      </geometry>
    </collision>
    <visual name="dummy_visual">
      <origin rpy="0  0  0" xyz="0    0    0.5"/>
      <geometry>
        <cylinder length="0.014" radius="0.003"/>
      </geometry>
    </visual>
  </link>

  <link name="dummy_prismatic_link">
    <inertial ...