[BUG] Duplicate enum key when generating enum values with sign

[jtzell]

Describe the bug
When the enum values different from each other by only sign characters (the "+" or "-"), the generator build code with duplicate enum definition.

To Reproduce
1./ Swagger file with following enum fields:

...
"tz": {"type": "string", "enum": [Etc/GMT", "Etc/GMT+0", "Etc/GMT+1", "Etc/GMT+10", "Etc/GMT+11", "Etc/GMT+12", "Etc/GMT+2", "Etc/GMT+3", "Etc/GMT+4", "Etc/GMT+5", "Etc/GMT+6", "Etc/GMT+7", "Etc/GMT+8", "Etc/GMT+9", "Etc/GMT-0", "Etc/GMT-1", "Etc/GMT-10", "Etc/GMT-11", "Etc/GMT-12", "Etc/GMT-13", "Etc/GMT-14", "Etc/GMT-2", "Etc/GMT-3", "Etc/GMT-4", "Etc/GMT-5", "Etc/GMT-6", "Etc/GMT-7", "Etc/GMT-8", "Etc/GMT-9", "Etc/GMT0"]}
...

2./ Running build will generated ".enums.swagger" with duplicate definition as follow:

...
@JsonValue('Etc/GMT-0')
etcGmt0,
@JsonValue('Etc/GMT-1')
etcGmt1,
@JsonValue('Etc/GMT-10')
etcGmt10,
@JsonValue('Etc/GMT-11')
etcGmt11,
@JsonValue('Etc/GMT-12')
etcGmt12,
...
@JsonValue('Etc/GMT-2')
etcGmt2,
@JsonValue('Etc/GMT-3')
etcGmt3,
@JsonValue('Etc/GMT-4')
etcGmt4,
@JsonValue('Etc/GMT-5')
etcGmt5,
@JsonValue('Etc/GMT-6')
etcGmt6,
@JsonValue('Etc/GMT-7')
etcGmt7,
@JsonValue('Etc/GMT-8')
etcGmt8,
@JsonValue('Etc/GMT-9')
etcGmt9,
@JsonValue('Etc/GMT0')
etcGmt0,
...
@JsonValue('Etc/GMT-0')
etcGmt0,
@JsonValue('Etc/GMT-1')
etcGmt1,
@JsonValue('Etc/GMT-10')
etcGmt10,
@JsonValue('Etc/GMT-11')
etcGmt11,
@JsonValue('Etc/GMT-12')
etcGmt12,
...
@JsonValue('Etc/GMT-2')
etcGmt2,
@JsonValue('Etc/GMT-3')
etcGmt3,
@JsonValue('Etc/GMT-4')
etcGmt4,
@JsonValue('Etc/GMT-5')
etcGmt5,
@JsonValue('Etc/GMT-6')
etcGmt6,
@JsonValue('Etc/GMT-7')
etcGmt7,
@JsonValue('Etc/GMT-8')
etcGmt8,
@JsonValue('Etc/GMT-9')
etcGmt9,
@JsonValue('Etc/GMT0')
etcGmt0,

Expected behavior
The generator should taking into account the sign characters when building enum definitions.
For example,

"tz": {"type": "string", "enum": [Etc/GMT0", "Etc/GMT+0","Etc/GMT-0"}
should output:
@JsonValue('Etc/GMT0')
etcGmt0,
@JsonValue('Etc/GMT-0')
etcGmtMinus0,
@JsonValue('Etc/GMT+0')
etcGmtPlus0,

Library version used:
2.2.1

Additional context
Add any other context about the problem here.

[Vovanella95]

Hi @jtzell , I will take a look to this. Thanks for raising issue