Error while building

[rvanheest]

Look up how this can be fixed. Appeared since we started using Java8, I think...

[INFO] Scanning for projects...
[INFO] 
[INFO] Using the builder org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder with a thread count of 1
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[INFO] Building RekeningSysteem Bouwbedrijf Mackloet v0.4-alpha
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[INFO] 
[INFO] --- maven-resources-plugin:2.6:resources (default-resources) @ Rekeningsysteem ---
[INFO] Using 'UTF-8' encoding to copy filtered resources.
[INFO] Copying 42 resources
[INFO] 
[INFO] --- maven-compiler-plugin:3.2:compile (default-compile) @ Rekeningsysteem ---
[INFO] Changes detected - recompiling the module!
[INFO] Compiling 232 source files to G:\Richard van Heest\Rekeningsysteem-Bouwbedrijf-Mackloet\Rekeningsysteem\target\classes
[INFO] Some messages have been simplified; recompile with -Xdiags:verbose to get full output
[INFO] -------------------------------------------------------------
[ERROR] COMPILATION ERROR : 
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[ERROR] /G:/Richard van Heest/Rekeningsysteem-Bouwbedrijf-Mackloet/Rekeningsysteem/src/main/java/org/rekeningsysteem/ui/textfields/PercentageFieldSkin.java:[30,25] variable control might not have been initialized
[ERROR] /G:/Richard van Heest/Rekeningsysteem-Bouwbedrijf-Mackloet/Rekeningsysteem/src/main/java/org/rekeningsysteem/ui/textfields/PercentageFieldSkin.java:[40,53] variable control might not have been initialized
[ERROR] /G:/Richard van Heest/Rekeningsysteem-Bouwbedrijf-Mackloet/Rekeningsysteem/src/main/java/org/rekeningsysteem/application/working/IOWorker.java:[57,77] incompatible types: bad return type in lambda expression
    rx.Observable<capture#1 of ? extends org.rekeningsysteem.data.util.AbstractRekening> cannot be converted to rx.Observable<? extends capture#2 of ? extends org.rekeningsysteem.data.util.AbstractRekening>
[INFO] 3 errors 
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[INFO] BUILD FAILURE
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[INFO] Total time: 6.027 s
[INFO] Finished at: 2015-08-19T09:03:06+01:00
[INFO] Final Memory: 16M/203M
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[ERROR] Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.2:compile (default-compile) on project Rekeningsysteem: Compilation failure: Compilation failure:
[ERROR] /G:/Richard van Heest/Rekeningsysteem-Bouwbedrijf-Mackloet/Rekeningsysteem/src/main/java/org/rekeningsysteem/ui/textfields/PercentageFieldSkin.java:[30,25] variable control might not have been initialized
[ERROR] /G:/Richard van Heest/Rekeningsysteem-Bouwbedrijf-Mackloet/Rekeningsysteem/src/main/java/org/rekeningsysteem/ui/textfields/PercentageFieldSkin.java:[40,53] variable control might not have been initialized
[ERROR] /G:/Richard van Heest/Rekeningsysteem-Bouwbedrijf-Mackloet/Rekeningsysteem/src/main/java/org/rekeningsysteem/application/working/IOWorker.java:[57,77] incompatible types: bad return type in lambda expression
[ERROR] rx.Observable<capture#1 of ? extends org.rekeningsysteem.data.util.AbstractRekening> cannot be converted to rx.Observable<? extends capture#2 of ? extends org.rekeningsysteem.data.util.AbstractRekening>
[ERROR] -> [Help 1]
[ERROR] 
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR] 
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/MojoFailureException