Continue removing guava dependencies

[coveralls]

Pull Request Test Coverage Report for Build 384

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 3 unchanged lines in 1 file lost coverage.
• Overall coverage increased (+0.7%) to 82.511%

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Files with Coverage Reduction	New Missed Lines	%
/home/travis/build/sjamesr/jfreesane/src/main/java/au/com/southsky/jfreesane/SaneClientAuthentication.java	3	95.0%
<!--	Total:	3		-->

Totals
Change from base Build 376:	0.7%
Covered Lines:	1906
Relevant Lines:	2310

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💛 - Coveralls