org.gradle.api
Interfaces 
Action
Buildable
DomainObjectCollection
DomainObjectSet
Instantiator
Named
NamedDomainObjectCollection
NamedDomainObjectContainer
NamedDomainObjectFactory
NamedDomainObjectSet
Namer
Plugin
Project
ProjectEvaluationListener
ProjectState
Rule
Script
Task
Transformer
Classes 
AntBuilder
DefaultTask
Named.Namer
Namer.Comparator
Task.Namer
Enums 
JavaVersion
PathValidation
Exceptions 
CircularReferenceException
GradleException
GradleScriptException
IllegalDependencyNotation
IllegalOperationAtExecutionTimeException
InvalidUserDataException
LocationAwareException
ScriptCompilationException
UncheckedIOException
UnknownDomainObjectException
UnknownProjectException
UnknownTaskException