Singular vs plural after "One example of such"

Question

In sentences like "One example of such X is Y" should X be singular, plural or can it be either?

For example:

Some methods are {description of this group of methods}.
One example of such methods is the {name of some specific method}.

Is this grammatically correct? Or should it be "one example of such a method" since we are talking about a singular example?

Another example:

These utilities form a significant portion of {...}.
One example of such a utility is a water cooling system.

I think, I've seen both singular and plural versions in fairly respectable sources, but now I'm having doubts if both are valid.

Here is a very similar question, but I'm not sure if similar reasoning applies here.

Answer 1

Both are often grammatical. The logical form (bolding mine):

• One example of such differences in regulatory treatment is the Standardised Approach in the CRR, which applies lower risk weights to certain ...

[Bank of England / European Central Bank]

(Compare 'Such differences in regulatory treatment are known to exist; one example is the Standardised Approach in the CRR'.)

Many such examples are to be found in a Google search for "one example of such" -"one example of such a"

...............

But the 'distributive singular' may also be used:

• Mass phishing campaigns are one example of such an attack.

[HM Government]

• [O]ne example of such a risk would be dangerous electrical installations or wiring.

[Bath and North East Somerset: Essential Information for Landlords and Agents]

Again, many such examples are to be found in Google searches for "one example of such a" / "one example of such an".

Answer 2

"One example of such a utility is a water cooling system."

This is correct. You are talking about one, so using the plural of utility (utilities) would be wrong.