Copy query parameter lists when building UriComponents

[cookie-meringue]

Current behavior

UriComponentsBuilder.build() copies the query parameter map but not the lists of values stored in it.
The builder and the resulting UriComponents can therefore share mutable query parameter lists.

Problem

Adding a value to an existing query parameter after build() can change the query of an earlier UriComponents result.

UriComponentsBuilder builder =
        UriComponentsBuilder.fromUriString("https://example.org?q=one");
UriComponents first = builder.build();
builder.queryParam("q", "two");
System.out.println(first.toUriString());
// https://example.org?q=one&q=two

A caller that retains first can therefore get a different URI when it uses the result later.

Fix

buildInternal() now creates a new LinkedMultiValueMap and copies the parameters with addAll(...), which creates an independent value list for each key.
The same example now produces:

UriComponentsBuilder builder =
        UriComponentsBuilder.fromUriString("https://example.org?q=one");
UriComponents first = builder.build();
builder.queryParam("q", "two");
System.out.println(first.toUriString());
// https://example.org?q=one