@Override
    public final boolean equals(Object o) {
        if (o == this) {
            return true;
        } else if (o instanceof SubQueryExpression) {
            SubQueryExpression<?> s = (SubQueryExpression<?>) o;
            return s.getMetadata().equals(queryMixin.getMetadata());
        } else {
            return false;
        }
    }
{@code FetchableQueryBase} extends the {@link QueryBase} class to provide default
implementations of the methods of the {@link com.querydsl.core.Fetchable} interface

@param <T> result type
@param <Q> concrete subtype

@author tiwe
querydsl-core/src/main/java/com/querydsl/core/support/FetchableQueryBase.java