Unicode characters are recognized

[saig0]

Describe the bug
Some Unicode characters are not recognized as Unicode. As a result, the Unicode is not handled correctly.

To Reproduce
Look at the following examples from the DMN-TCK:

string length("\U01F40E")
// expected: <1> but was <8>

"\U01F40E" = "🐎"
// expected <true> but was <false> 

string length("\\u0009")
// expected <6> but was <7>

string length("\uD83D\uDCA9")
// expected <1> but was <2>

string length("\ud83d\udca9")
// expected <1> but was <2>

string length("\ud83d\udc0e\uD83D\uDE00")
// expected <2> but was <4>

string length("🐎😀")
// expected <2> but was <4>

substring("\U01F40Efoo", 2) = "foo"
// expected <true> but was <false>

Expected behavior
Unicode characters are handled correctly. See the DMN-TCK for reference.

Environment

• FEEL engine version: 1.15.2
• Affects:
  • Camunda Automation Platform 7: [7.x]
  • Zeebe broker: [0.x]