To Reproduce:

1. From [Filesystems] tab in [Explorer] window, right click web.xml file
   (e.g. web.xml file in "CD Shop Cart", which is bundled in FFJ),
   and select [properties].

2. From [Reference] tab in [Properties] window, 
   click [...] in right side of [Environment Entries] row.
   [Property Editor: Environment Entries] window is appeared.

3. click [Add].
   [Add] window is appeared.

4. Input for any name in [Name] field, select [java.lang.float] in [Type],
   and input Fullwidth Digits in [Value] field, and click [OK].
   Error has occurred.
   
See Also 1:
   In step 4, select [java.lang.integer].
   -> http://www.netbeans.org/issues/show_bug.cgi?id=20335

See Also 2:
1. From [Filesystems] tab in [Explorer] window, right click web.xml file
   (e.g. web.xml file in "CD Shop Cart"), and select [properties].

2. From [Deployment] tab in [Properties] window, 
   click [...] in right side of [Session Timeout] row.
   [Property Editor: Session Timeout] window is appeared.

3. [In Minute] check box is turned on, input Fullwidth Digits
   in [minute] text box, and click [OK].
   Corresponding single-byte Digits are stored in property window
   and web.xml file with no errors.

WorkAround: 

When [java.lang.float] is selected from [Type] Drop-Down List, 
and input Fullwidth Digits, 
corresponding digits are stored in [Value] field.

But, [java.lang.float] is selected, 
it allowed input same characters except for the digits.
The following characters are converted, too.

   1) Digits (0-9) [required]
        "FULLWIDTH DIGIT" are "FF10 - FF19",
            "DIGIT" are "0030 - 0039",
                in the unicode character list.

   2) "."¡¤"-" [important]
	FULLWIDTH FULL STOP (FULLWIDTH PERIOD) is "FF0E"
            FULL STOP (PERIOD) is "002E", 
        FULLWIDTH HYPHEN-MINUS is "FF0D",
            HYPHEN-MINUS is "002D",
                in the unicode character list.

   3) "E" as Exponential Mark¡¤"infinity" strings [Lowest Priority]
        FULLWIDTH LATIN CAPITAL LETTER "E" is "FF25"
            LATIN CAPITAL LETTER "E" is "0045"
        FULLWIDTH LATIN SMALL LETTER are "FF41 - FF5A"
            LATIN SMALL LETTER are "0061 - 007A"       
                in the unicode character list.
        The string "infinity" is combination of "LATIN SMALL LETTER".