@SuppressWarnings("unchecked")
    public final boolean equals(Object o) {
        if (o == this) {
            return true;
        } else if (o instanceof SubQueryExpression) {
            SubQueryExpression<T> s = (SubQueryExpression<T>) o;
            return s.getMetadata().equals(metadata);
        } else {
            return false;
        }
    }
{@code SubQueryExpressionImpl} is the default implementation of the {@link SubQueryExpression} interface

@author tiwe
@param <T> Result type
querydsl-core/src/main/java/com/querydsl/core/types/SubQueryExpressionImpl.java