Fix for issue when attempting to insert an empty or null value on encrypted column

[ulvii]

Workaround for #624.
Currently, when inserting empty string or null into encrypted variable-length columns, the driver sets the data length to 0 and the type to type(0) (varchar(0) for example). The workaround is to set the length to 1 and the type to type(1).

[codecov-io]

Codecov Report

Merging #632 into dev will increase coverage by 0.06%.
The diff coverage is 62.5%.

@@             Coverage Diff             @@
##               dev     #632      +/-   ##
===========================================
+ Coverage     46.5%   46.57%   +0.06%     
- Complexity    2227     2231       +4     
===========================================
  Files          109      109              
  Lines        25431    25439       +8     
  Branches      4190     4190              
===========================================
+ Hits         11827    11848      +21     
+ Misses       11566    11546      -20     
- Partials      2038     2045       +7

Flag	Coverage Δ	Complexity Δ
#JDBC42	46.48% <62.5%> (+0.16%)	2224 <0> (+5)	⬆️
#JDBC43	46.31% <62.5%> (-0.04%)	2224 <0> (+5)

Impacted Files	Coverage Δ	Complexity Δ
...n/java/com/microsoft/sqlserver/jdbc/Parameter.java	62.44% <62.5%> (ø)	63 <0> (ø)	⬇️
...om/microsoft/sqlserver/jdbc/ReaderInputStream.java	44.94% <0%> (-3.38%)	16% <0%> (-2%)
...om/microsoft/sqlserver/jdbc/SimpleInputStream.java	51.11% <0%> (-1.49%)	11% <0%> (-1%)
...c/main/java/com/microsoft/sqlserver/jdbc/Util.java	60.91% <0%> (-0.66%)	88% <0%> (-1%)
...rc/main/java/com/microsoft/sqlserver/jdbc/dtv.java	62.84% <0%> (-0.13%)	0% <0%> (ø)
...om/microsoft/sqlserver/jdbc/SQLServerBulkCopy.java	52.8% <0%> (+0.19%)	241% <0%> (+1%)	⬆️
...in/java/com/microsoft/sqlserver/jdbc/IOBuffer.java	54.4% <0%> (+0.19%)	0% <0%> (ø)	⬇️
...m/microsoft/sqlserver/jdbc/SQLServerResultSet.java	33.36% <0%> (+0.32%)	247% <0%> (+5%)	⬆️
...rc/main/java/com/microsoft/sqlserver/jdbc/DDC.java	45.59% <0%> (+2.03%)	105% <0%> (+2%)	⬆️

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[peterbae]

The workaround looks fine. After looking around the code, it seems like the valueLength is 0 if the user is using a callable statement and using the parameter as an output parameter. Have you considered this case / looked into what giving n/varchar(1) to the server implies?

[peterbae]

I think it should be fine since I just tried the same scenario with output parameter, and it seems to work fine, but I wanted you to consider this scenario as well.

[ulvii]

I tested the PR with both PreparedStatement and CallableStatement.