private ImmutableMap<String, ExecutableElement> methodsOf(TypeElement type, int argumentCount) {
    return ElementFilter.methodsIn(elementUtils.getAllMembers(type)).stream()
        .filter(method -> method.getParameters().size() == argumentCount)
        .filter(method -> !isStaticInterfaceMethodNotIn(method, type))
        .collect(
            collectingAndThen(
                toMap(
                    method -> method.getSimpleName().toString(),
                    Function.identity(),
                    (method1, method2) -> method1),
                ImmutableMap::copyOf));
  }
The method to copy another collection into this builder. It is {@code addAll} for
one-dimensional collections like {@code ImmutableList} and {@code ImmutableSet}, and it is
{@code putAll} for two-dimensional collections like {@code ImmutableMap} and {@code
ImmutableTable}.
value/src/main/java/com/google/auto/value/processor/PropertyBuilderClassifier.java