public void onBlockAdded(World worldIn, BlockPos pos, IBlockState state) {
		TileEntityHoloStand te = (TileEntityHoloStand) worldIn.getTileEntity(pos);
		te.setOwnerUUID(worldIn.getClosestPlayer(pos.getX(), pos.getY(), pos.getZ(), 5, false).getUniqueID());
		owner = te.getOwnerUUID();
        ....
}

package io.ryanshah.mobholo.block.tileentity;

import java.util.UUID;

import net.minecraft.nbt.NBTTagCompound;
import net.minecraft.tileentity.TileEntity;

public class TileEntityHoloStand extends TileEntity
{
	protected UUID ownerUUID;

	public void readFromNBT(NBTTagCompound compound) {
		super.readFromNBT(compound);

		this.ownerUUID = compound.getUniqueId("Owner");
	}

	public NBTTagCompound writeToNBT(NBTTagCompound compound) {
		super.writeToNBT(compound);

		compound.setUniqueId("Owner", ownerUUID);

		return compound;
	}

	public UUID getOwnerUUID() {
		return ownerUUID;
	}

	public void setOwnerUUID(UUID uuid) {
		ownerUUID = uuid;
	}
}