Illegal reflective access operation

[70853n]

WARNING: An illegal reflective access operation has occurred
WARNING: Illegal reflective access by uk.org.webcompere.systemstubs.environment.EnvironmentVariables (file:/Users/user/.m2/repository/uk/org/webcompere/system-stubs-core/1.2.0/system-stubs-core-1.2.0.jar) to field java.util.Collections$UnmodifiableMap.m
WARNING: Please consider reporting this to the maintainers of uk.org.webcompere.systemstubs.environment.EnvironmentVariables
WARNING: Use --illegal-access=warn to enable warnings of further illegal reflective access operations
WARNING: All illegal access operations will be denied in a future release

[ashleyfrieze]

Duplicate of #32

[ashleyfrieze]

@70853n I've left a long explanation in #32