Stained glasses are becoming invisible bedrock

[joserobjr]

Affected Version
2.0.0-SNAPSHOT

Describe the bug
After conversion, the stained glasses are incorrectly becoming invisible bedrock (similar to barrier)

To Reproduce
Steps to reproduce the behavior:

1. Have a 1.8.9 spigot world which contains stained glasses
2. Optimize it on 1.14.2
3. Convert to Nukkit without errors
4. Replace the Nukkit world with the converted world
5. Launch Nukkit and go to the stained glasses location
6. See an invisible bedrock there

Expected behavior
Keep the stained glasses as stained glasses

Exception stack trace
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No erro logged

Screenshots
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Additional context
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