Texture loading in LWJGL 3
This is a pretty straightforward and readable implementation, and I see how it can be used. Here are some suggestions:
Use Modern OpenGL
It looks like you're using OpenGL 1.x. That's really old OpenGL. You should be using OpenGL 3 or later, really. It's supported on all major platforms. It's not too difficult to learn if you already know OpenGL 1 and it offers a lot of benefits.
Keep Track of Your Texture Target
While a texture ID is certainly an important piece of information to keep around, it's not the only piece you need. Almost all texture-related functions in OpenGL require a texture target instead of or in addition to a texture ID. If you don't keep it around you'll either end up needing it and not having it, or being forced to always use one particular texture target, which is not ideal.
Naming
While your variable names are decent, they could be even better. For example, in both resizeBuffer() and imageToByteBuffer() you have an argument named size. What units is size in? Bytes? Pixels? Vertices? You should be more explicit with a name like numBytes or size_in_bytes, or whatever's appropriate.
Also the function name imageToByteBuffer() is confusing. From the name, it seems like it's going to read a file at a path and return a byte buffer containing the pixels from the image at that path. But the second half of the function looks like it does something else. I'm not familiar enough with the Java libraries to understand when file.isFile() would return false, and what else a file would be if not a file. (I assume since it's a URL it might be a network resource?) I would recommend making 2 functions - one for reading a local file and one for reading a remote file (or whatever the else path does), with appropriate names and call them from imageToByteBuffer. Something like this:
if (file.isFile())
{
    return imageFromLocalFile(path);
}
else
{
    return imageFromRemoteFile(path, size); // or whatever it should be called
}

Also, how does a caller know what to pass in for size? Isn't that something that is discovered by reading the file?